A Summary Of "Being And Being Known" by Wilfred Sellars

1. Sellars aims to defend the claim that there is an isomorphism between the knower and what is known while disputing the Thomistic understanding of this doctrine. 

2. According to Sellars, this examination is important because many central Thomistic contentions, such as their belief in the immateriality of the intellect, are based upon their understanding of this isomorphism.

3. He begins his explication of the Thomistic doctrine by contrasting it with the account of intellectual acts found in Descartes and the account found in early stages of contemporary British and American realism.

4. According to Sellars, these latter views are united by the idea that intellectual acts are distinguished in terms of what they are related to, rather than in terms of their intrinsic character as intellectual acts.

5. Sellars suggests that this idea leads to unacceptable philosophical consequences. His preferred alternative is to hold that the intrinsic characters of intellectual acts differ in ways that systematically correspond to differences in what those acts are about. The most serious doctrine of this sort, he claims, is the “doctrine of the mental word”.

6. According to the Thomistic doctrine of the mental word, Sellars claims, a mental word is a nature or form that informs the intellect in a way the enables that intellect to think particular thoughts that are about that nature or form.

7. Since, according to Sellars, we are tempted to say that the intellect does not take on the form that informs it in the same way that material objects do, we are led to conclude that the nature or form is informing the intellect in the “immaterial mode”. 

8. Sellars’s Thomist holds that a nature or form can inform the intellect only because it initially informs their sensory faculties in the immaterial mode. The former sort of informing is grounded upon the latter sort. Thus, he says that we can speak of the sensible as well as the mental word. 

9. Sellars holds that the Thomistic conception of intellectual abstraction depends upon their claim that our sensory faculties exhibit an independent form of intentionality that can serve as a basis for the emergence of intellectual intentionality.

10. In contrast to the Thomist, Sellars argues that we can formulate an alternative account of sensory forms that is not committed to the idea that sensory faculties are informed in the immaterial mode. According to this alternative account, sensory experiences involve specific forms in a “derivative sense” that can be analyzed in terms of certain causal relations between types of sensations and types of external objects.

11. Sellars highlights the contrast between the views under consideration as follows: According to the Thomist, material objects and sensations involve the same form in distinct (material or immaterial) modes. According to Sellars, material objects and sensations involve different forms that are specified by different senses of the same word. 

12. On Sellars’s alternative proposal, there is a structural isomorphism between the types of external objects specified by words used in one sense and the types of sensations specified by those words used in another, derivative sense. 

13. Sellars does not focus on arguing for his alternative view of the isomorphism between nature and sensations. Rather, he simply adds that his alternative view entails that the abstractive theory of mental word acquisition is false and that abstractive theories face other difficulties relating to other logical mental words as well (these difficulties can be viewed as a reason to accept Sellars’s view of the isomorphism rather than the Thomist’s).

14. On Sellars’s account, the isomorphism between nature and the senses is a structural isomorphism between external causes and sensory acts that requires no appeal to the possibility of external objects and sensations being informed by a common form in distinct modes. In light of this thesis, he now proposes to argue that there is a similar isomorphism between thought and the world. Furthermore, he holds that this isomorphism between thought and the world is a necessary condition for mental intentionality.

15. Sellars argues that mental words can be understood as “words” in a novel sense that is derived from the sense that applies to linguistic tokens. Like linguistic tokens, he argues, there is a structural isomorphism between specific mental words and specific objects in reality that is determined by a causal relationship between them. This is the isomorphism that he claims is necessary for mental intentionality. 

16. Sellars views claims about the isomorphism between mental words and objects in reality as statements that relate certain tokens, considered as meaningless, to other objects in the external world. By contrast, Sellars views claims about intentional significance as statements that relate certain tokens, considered as meaningful, to tokens of our own language (and other languages) in terms of their role within their own “language”. 

17. By formulating an account of these two sorts of isomorphism, Sellars aims to explain mental intentionality in a way that 1. Doesn’t require mental words that are related to absolute natures by being informed in an immaterial mode, and 2. accounts for how our mental words are related to mind-independent reality.

Thinking And Being: Key Terms

I am trying to compile a list of the key terms (along with their explanations) found in Irad Kimhi's Thinking And Being. The current list can be found here.

Section 293 Of Philosophical Investigations

In section 293 of Philosophical Investigations, Wittgenstein considers the idea that human subjects only know the meaning of the word “pain” on the basis of their own experiences of pain. The passage runs as follows:

293. If I say of myself that it is only from my own case that I know what the word "pain" means—must I not say the same of other people too? And how can I generalize the one case so irresponsibly? Now someone tells me that he knows what pain is only from his own case!——Suppose everyone had a box with something in it: we call it a "beetle". No one can look into anyone else's box, and everyone says he knows what a beetle is only by looking at his beetle.—Here it would be quite possible for everyone to have something different in his box. One might even imagine such a thing constantly changing.—But suppose the word "beetle" had a use in these people's language?—If so it would not be used as the name of a thing. The thing in the box has no place in the language-game at all; not even as a something: for the box might even be empty.—No, one can 'divide through' by the thing in the box; it cancels out, whatever it is. That is to say: if we construe the grammar of the expression of sensation on the model of 'object and designation' the object drops out of consideration as irrelevant.

It may be tempting to interpret the upshot of Wittgenstein’s remarks here in the following way: In order to successfully use a name to refer to some object, that object must be related to the way our linguistic community uses the relevant name. However, in the imagined scenario, since the specific object in each speaker's box is not relevant to their use of the term ‘beetle”, they are not using the word “beetle” as a name for the private objects in their boxes. Likewise, private sensations are not related to the way our linguistic community uses the word “pain” so it does not name private objects that each of us experiences. 

This interpretation might appear to highlight an important continuity between the early Wittgenstein and his later work. In the Tractatus Logico-Philosophicus, Wittgenstein seems to present conditions for meaningful speech about reality. He then seems to show that these conditions cannot be satisfied by speech about language, ethics, and the self, among other philosophical subjects. This interpretation places the reader in a paradoxical situation: In order to recognize that one cannot meaningfully speak about language, ethics, and the self, one must first know that the nature of language does not allow for such speech. But this would seem to imply that Wittgenstein’s speech about language is meaningful after all. The solution, according to some interpreters of Wittgenstein, involves recognizing that, although Wittgenstein’s propositions in the Tractatus are, strictly speaking, nonsensical, they nevertheless make us aware of important ineffable truths about the nature of language. 

If one accepts this interpretation of the early Wittgenstein, section 293 of Philosophical Investigations can be understood as a new application of the old philosophical method. Wittgenstein presents certain conditions that must be met by meaningful speech and shows that speech about private objects does not meet those conditions. However, on this view, the fact that the conditions for meaningfulness cannot be satisfied by our speech about private objects does not imply that there are no private objects in experience. Like the truths of the Tractatus that render us silent regarding that which cannot be spoken about, these truths about experience may simply be ineffable. 

In my view, this general approach is mistaken as an interpretation of the early, as well as the later, Wittgenstein. What Wittgenstein seeks to show us, in Philosophical Investigations, is not that conditions on meaningful speech prevent us from speaking about private objects that may or may not be present. Rather, his remarksp are intended to highlight the fact that we do not use the term “pain” as the name for an object at all. At no point in his remarks does the later Wittgenstein concern himself with how we must speak or what we must speak about in order to speak meaningfully. Rather, in all cases, he simply aims to describe how we do, in fact, use our words. 

Returning to the imagined community of section 293, what this scenario presents is a situation in which a group of speakers do not use the term “beetle” as a name for the object in their box. What it does not present is a situation in which a group of speakers are confronted with private objects that cannot be named. Suppose that each speaker’s box did, in fact, contain a beetle. We can easily imagine a scenario in which a group of speakers opened each other’s box, examined the sort of thing that was inside each of them, and collectively decided to use the word “beetle” as a name for things of that sort. The fact that they do not do this in Wittgenstein’s scenario only shows that the use of the term “beetle” in his example is not what we would call the use of a name. Furthermore, in recognizing that their term “beetle” does not name objects inside of their boxes, we are not thereby committed to claiming that the objects in their boxes cannot be named. 

In a similar fashion, what Wittgenstein’s example shows is that our use of the term “pain” is not the use of a name for an object. What we call a “use of a name” is a use of a word that is responsive to the sort of thing we are naming and how things stand with respect to it. But, as Wittgenstein shows in 293 and the surrounding sections of Philosophical Investigations, this is not how we use the term “pain”. By reflecting on our use of the term “pain”, Wittgenstein aims to show us that it is not the use of name and that, on the basis of similar considerations, it is unclear what the claim “...it is only from my own case that I know what the word "pain" means.” is actually supposed to mean. 

It is crucial to emphasize that Wittgenstein’s remarks in section 293 do not represent a move towards any form of behaviorism or eliminativism about mentality. As he goes on to note in section 304, he believes that there could hardly be a “greater difference” between pain and pain-behavior. Furthermore, he claims that “[Pain] is not a something, but not a nothing either!”. To claim that mentality is nothing other than behavior would be to hold that pain is, in fact, something that exists. But Wittgenstein’s latter remark is intended to highlight the fact that claiming some X does or does not exist only happens within a certain sort of language game. Specifically, it only happens in a language game that involves using a name for the relevant object. By denying that pain is a something or a nothing, Wittgenstein is simply pointing out that such affirmations have no role that is connected to our actual use of the word “pain”. For Wittgenstein, behaviourist and eliminativist theses depend upon the same misunderstandings that so-called “realism” exhibits. 

In conclusion, I would like to make some brief remarks on Wittgenstein’s diagnosis of the error that is highlighted by section 293 and discuss its relation to his early work. In section 125 of Philosophical Investigations, Wittgenstein describes the “fundamental fact” that gives rise to a need for philosophical reflection. This fact, he claims, is that “... we lay down rules, a technique, for a game, and that then when we follow the rules, things do not turn out as we had assumed.” He goes on to say that “...we can avoid ineptness or emptiness in our assertions only by presenting the model [of a language game] as what it is, as an object of comparison—as, so to speak, a measuring-rod; not as a preconceived idea to which reality must correspond.” (S.131). This temptation to understand our use of language in terms of a preconceived model is what Wittgenstein calls “dogmatism” in philosophy.

The error that Wittgenstein highlights in section 293 is one form of philosophical dogmatism. Specifically, it is a commitment to the preconceived notion that our use of the term “pain” can be understood “on the model of 'object and designation'”. (S.293) Wittgenstein believes that this error can be overcome once “we make a radical break with the idea that language always functions in one way, always serves the same purpose: to convey thoughts—which may be about houses, pains, good and evil, or anything else you please.” (S.304) In other words, once we recognize that the word “pain” is not necessarily used to try and designate a certain object, we can overcome our tendency to think that pain must be a something or a nothing. 

The recognition that causes that philosophical puzzle to disappear also dissolves the apparent paradox at the heart of the Tractatus. The interpretation of the Tractatus considered earlier claims that Wittgenstein presents a theory of meaning and language that implies that his own propositions are nonsensical. This seems to suggest that, if his book succeeds, he must be using nonsensical propositions to make the reader aware of ineffable truths. However, if we follow the later Wittgenstein’s rejection of dogmatism, we can recognize that language is not always used to describe facts about reality. Rather, as Wittgenstein notes in section 295, philosophy provides “A full-blown pictorial representation of our grammar. Not facts; but as it were illustrated turns of speech.” To understand this passage is to understand that philosophical propositions can serve a purpose that does not involve conveying truths of any sort. They do not need to involve any attempt to speak where we must remain silent. In my view, this was already understood by the early Wittgenstein when he insisted that his nonsensical propositions were nevertheless “elucidatory.” Insofar as he later came to view his own efforts in the Tractatus dogmatic, the relevant form of dogmatism must be located elsewhere.

The Search For A Logical Robot: Critical Remarks On Artificial Intelligence

The recent history of technological development has raised significant questions regarding the future possibility of genuine artificial intelligence. Specifically, many scientists and philosophers (along with the general public) have become increasingly convinced that it will someday be possible to use technological innovations in order to construct a being capable of thinking and reasoning in the same ways that human beings do. In addition to the popular worries that this has raised concerning the practical risks and metaphysical implications that such a being would present, these speculations have also led many to reflect on how such a being could be identified, were one to emerge. 

These reflections have received further encouragement from the advent of large language models such as ChatGPT, which emulate human speech patterns with an astonishing degree of accuracy. Indeed, some computer scientists have already been fully persuaded that ChatGPT is a genuine rational subject that deserves to be treated as such. However, to what extent are these convictions justified? In order to answer this question, we must first investigate what the appropriate criteria for identifying the emergence of genuine artificial intelligence could possibly be. The success of this investigation, in turn, will depend on a proper conception of intelligence as such.

In a recent article, Jensen Suther surveys contemporary philosophical thought on artificial intelligence and highlights several plausible requirements that any intelligent being must satisfy. One of these requirements, famously defended by Hubert Dreyfus, holds that any genuine intelligence must be embodied. When we think about genuinely intelligent behavior, one of its core elements involves an ability to modify one’s behavior in light of success or failure. If a being has no capacity to receive data, act in light of that data, and adjust its behavior in light of the results of their activity, then in what sense can it be said to be reasoning at all? If we accept that this capacity for informed behavioral modification is a real requirement for intelligence, there are two important implications: First, any genuinely intelligent being must have some sort of body capable of behaving in certain ways and having that behavior modified in light of incoming data. Second, that being must have some determinate goal that informs how it modifies its behavior in light of incoming data. In the absence of some goal, there would be nothing to guide its behavioral modification and, consequently, no basis for distinguishing intelligent behavioral modification from unintelligent modification, so this latter feature is just as necessary as the former. Together, we can call them “the embodiment criterion”. 

However, even if we accept the embodiment criterion for genuine intelligence, there is another key feature which any intelligent being must possess: Intelligent beings, by thinking, must be capable of determining their own activity as embodied beings. We can call this the “self-determination criterion”. On the face of it, this criterion seems straightforward enough. By thinking and reasoning, intelligent creatures can decide what they should do in light of what is the case and act accordingly. However, in what sense can an agent be genuinely self-determining if it cannot determine the principles that govern its own acts of thinking and reasoning? If an artificial being is pre-programmed with rules for thinking or methods for forming such rules, then its own “rational” procedures are determined by a source that is wholly external to it. If it is not pre-programmed with rules or rule-forming methods, then it is hard to see how it can be said to have rule-governed behavior at all. In the former case, it seems like the agent is governed by external constraints in a way that is incompatible with genuine intelligence. In the latter case, it seems unconstrained in a way that is also incompatible. 

For human beings, a solution to this dilemma is possible: When human beings think, they also place themselves under a shared set of rules that characterize the thoughts of the intellectual community that they are a part of. By taking on the responsibility to think in accordance with these rules, these rules govern their particular acts of thinking without being pre-programmed in them by any external source. To the extent that the rules governing human thinking are established by a community, human thinking can be said to be a socially constituted phenomenon that is self-imposed by individual thinkers. Furthermore, human thinkers remain genuinely self-determining insofar as they collectively shape the public rules that govern them by reasoning with one another. 

However, this solution to the dilemma posed by self-determination is not obviously available in the case of artificial intelligence. The reason why human beings can defer to socially instituted rules of thought is because human beings recognize one another as potential thinkers that they can treat as rule-governed subjects. It is because they are recognized as potential thinkers that it is possible for them to place themselves under the rules of their intellectual community and be held responsible for them. But in the case of AI, this potential for intelligence is precisely what is at issue. Insofar as their potential for intelligence is not recognized, they will not be recognized as potentially rule-governed subjects. Consequently, they will not be able to place themselves under the rules that govern our intellectual community and thereby satisfy the self-determination criterion. 

The moral of the above considerations is as follows: The possibility of genuine intelligence requires a being to be an embodied member of an intellectual community that recognizes them as a potential thinker. This is the only way that an agent can satisfy the embodiment criterion as well as the self-determination criterion. Human beings recognize other human beings as potential thinkers because they recognize themselves as intelligent creatures of the same sort. They recognize each other as deferring to public rules because they understand what cases of deference look like for creatures of the sort that they are. However, this recognition does not extend to non-human agents. We cannot treat such beings as potential thinkers because we do not know whether and when they are capable of deferring to public rules. In order to know that, we would have to know something about the nature of their life form. But artificial agents have no life form to know about. They are not alive. 

Recent developments in technology have given rise to two questions: Is genuine artificial intelligence possible and, if so, can we identify when it is present? As this discussion suggests, it is a mistake to view these questions as separate from one another. The possibility of genuine artificial intelligence depends upon the ability of humans, or some other rational creatures, to recognize when it is present. This is the only way for artificial intelligence to satisfy the self-determination criterion. It is not possible for artificial intelligence to be identified in this way because it bears no recognizable form of life. If the search for a logical robot is to reach its conclusion, it cannot simply involve the production of artificial intelligence alone. Rather, as Jensen Suther notes, “we can’t produce artificial intelligence without also producing artificial life.”

"Hegel Against The Machines" by Jensen Suther: https://www.newstatesman.com/ideas/2023/07/hegel-against-machines-ai-philosophy?mibextid=Zxz2cZ

How Is A Priori Knowledge Possible? An Argument For Absolute Idealism

 [This post is a sequel to my previous post, “On The Immateriality Of Mind”]

What is a priori knowledge and how can we possibly attain it? In order to answer these questions, we must first reflect on knowledge and its conditions more generally. At a minimum, if I (or any rational subject) knows something, we believe what we know truly on an appropriate basis. However, is this all that is required? Many philosophers have objected to this proposal as an account of the sufficient conditions for knowledge on the grounds that there are clear cases where true beliefs formed on an appropriate basis still fail to qualify as genuine knowledge (these are the famous “gettier cases” and their variants). I would like to set these cases aside for the moment. Regardless of how they are ultimately addressed, there is a further puzzle facing any account of the possibility of genuine knowledge. Namely, even if we did have a sufficient basis for knowledge available to us, would this alone be sufficient for us to be in a position to form true beliefs on that basis?

It seems to me that a sufficient basis of this sort would not be enough for us to understand how it is possible for us to form true beliefs. In order for me to form a belief on some basis, I cannot simply be aware of that basis. Rather, I must also recognize that my belief is formed upon a basis that is sufficient for genuine knowledge. If I lack this awareness then, for all that I am reflectively aware of, my basis may, in fact, be insufficient. In other words, in forming my belief upon that basis, I would still not be able to satisfy myself that my belief is, in fact, true. For all that I am reflectively aware of in forming my belief that P, it is nevertheless open to me that, possibly, P is not the case. But if I am in a position where I can entertain the possibility that P is not the case, given all that I am reflectively aware of, then I do not genuinely believe it at all. To believe that P is to hold that P is what is actually the case, and to arrive at such a belief with the aim of thinking what is true, I must recognize some basis which I take to be capable of settling the question, “P or not-P?” 

Insofar as I take the reasons that explain my belief to be what settles the question, “P or not-P?” I must think that the truth of my belief is ensured by the reasons that lead me to form my belief. In other words, if I form my belief upon some basis, I cannot then proceed to investigate whether or not my basis for forming that belief is sufficient for ensuring its truth. If I believe that P, I must, in forming that belief, already be satisfied that my basis for believing is sufficient. This raises a question: How can we have knowledge that the causes of our beliefs is sufficient for knowledge unless we already possess some sort of knowledge about thinking and its proper explanation in the first place? On the one hand, if we say that we do not possess such knowledge, then it seems that we must admit the possibility of beliefs that are formed in the absence of an awareness that those beliefs have a sufficient basis for knowledge. On the other hand, if we maintain that we do possess such knowledge, then, on pain of circularity, it would seem that this knowledge cannot depend on our awareness of any sufficient basis at all. Solving this puzzle is what requires us to account for the possibility of a priori knowledge. It requires us to account for the possibility of satisfying ourselves of the truth of our beliefs without being aware of any sufficient basis for forming them.

If I believe that Socrates is a mortal because of the facts that all men are mortal and that Socrates is a man, then I recognize my reasons for belief as a sufficient basis for my belief that Socrates is a mortal. This requires me to know that my beliefs, when they are explained by certain reasons, are explained by reasons that ensure the truth of my beliefs. If I did not already know this, then it would remain open for me to doubt whether my reasons for believing that Socrates is a mortal were, in fact, good reasons for believing that. In this case, all that was reflectively available to me would not enable me to settle the questions “Is it the case that Socrates is a mortal?” But I am able to settle that question when I form that belief for those reasons because I do know that my beliefs are explained by reasons that ensure the truth of what I believe. In other words, I know that judgment is a certain sort of power that, when exercised, produces knowledge. I know that judgment is a power of knowledge.

However, as noted previously, we must still account for my knowledge of this very power. How can I know that judgment is a power of knowledge if this knowledge is already presupposed whenever I form beliefs on the basis of reasons? If it is required in order for me to form beliefs on the basis of reasons in the first place, then this knowledge cannot itself depend upon any reasons for belief. Rather, it must be a priori. How then, can I take what I believe, in knowing that judgment is a power of knowledge, to be true? 

When we believe on the basis of good reasons, we take the basis of our beliefs to ensure the truth of those beliefs. If we believe something without any such basis, in order to be satisfied that our beliefs are true, we must be in a position to recognize their truth in the absence of any basis. In other words, we must be satisfied that their truth is ensured in the absence of any basis apart from our believing them. When we believe that judgment is a power of knowledge, this belief cannot depend on anything other than the activity of thinking itself. If it did, then it would remain open that, despite believing that judgment is a power of knowledge, my belief might nevertheless be false. In order for this knowledge to be a priori, I must know that the truth of my belief does not depend on anything other than my activity of thinking alone. I must know that thinking itself ensures the reality of the power that it is and, consequently, can know itself to be such a power in the absence of any independent basis for forming such a belief. 

This is how it must be with a priori knowledge in general. In order to know something, independently of any basis, I must know that the activity of thinking itself ensures the reality of what it knows, a priori. Insofar as a knowledge of the nature of thought, as a power of judgment, must be a priori, we must know that the reality of that nature is ensured by the activity of thinking itself. In this sense, we can say along with Jean-Paul Sartre that, with respect to thinking, essence does not precede existence. However, we must oppose Sartre when he says that existence precedes essence. The nature of thought and its activity do not stand in any relation of priority with respect to one another. Rather, the essence of thinking is one and the same as its activity. 

The reality of our a priori knowledge of the nature of thought establishes that thinking alone ensures the truth of what it thinks about its own nature. However, our a priori knowledge is not limited (and cannot be limited) to the nature of thought as such. Our a priori knowledge also includes the principles that govern reality in its entirety. In other words, we possess a priori knowledge of the laws of logic. Insofar as we know, a priori, that any fact opposes the negation of that fact (the law of non-contradiction) and that, for any possible fact, it either obtains or does not obtain (the law of excluded middle), the laws of logic are known independently of any mind-independent basis. Following the remarks made above, this entails that the reality of these laws must be known to be ensured by the activity of thinking alone. In other words, the nature of Being, along with the nature of Thought, must be known to be ensured by the activity of thinking alone. Indeed, just like the nature of thought, the nature of Being must be one and the same as the activity of thinking.

The conclusion specified in the final remarks of the preceding paragraph can be formulated in another way: Thinking and Being are the same. This is the formula of Absolute Idealism. This sameness is known, a priori, in any judgment, insofar as a thinker is satisfied that their judgment is true. Insofar as we make judgments on the basis of reasons, these judgments depend on a priori knowledge that does not, and is known not to, require any such basis. The truth of this knowledge must be known to be ensured independently of anything apart from the activity of thinking itself. Insofar as our a priori knowledge is a knowledge of the nature of Thought (the principles of thinking) and the nature of Being (the principles of logic), we must know that the reality of these natures is nothing apart from the reality of the very same activity. 

The ancient philosopher, Parmenides, famously wrote that “It is the same thing that can be and that can be thought”. Aristotle followed his insight by treating the metaphysical principle of non-contradiction as one and the same as the psychological principle of non-contradiction (Metaphysics, 4.3). These philosophers are articulating their knowledge that the activity of thinking is the same as the activity of Being. In order for contemporary philosophy to successfully address the myriad of puzzles that it has consistently failed to overcome, this knowledge must ultimately be recovered.

On The Immateriality Of Mind

C.S. Lewis argued that, if we conceive of rationality and judgments as a physical organ and its products, then we cannot consistently hold that any of our beliefs are rationally explained, as opposed to solely being causally explained. 

In reply, some philosophers have suggested that Lewis mistakenly inferred that, if rationality and judgements have a sufficient causal explanation, they must lack a rational explanation. According to these philosophers, Lewis failed to show that rational and causal explanations are incompatible with one another. Insofar as this incompatibility has failed to be established, they conclude, Lewis cannot claim to have shown that naturalism precludes rational explanation.

Can anything be said on Lewis’s behalf? It seems to me that, when we reflect on what a “rational explanation” really amounts to, it can be shown that there is indeed an incompatibility of precisely the sort that Lewis’s argument requires. 

One objection that has been raised against Lewis is the claim that “reasons explanations” are  distinct, non-causal sorts of explanations that are different from, but not incompatible with, causal explanations. On this view, when we provide reasons for our beliefs, we are not appealing to the causes of our beliefs. Rather, we are placing our belief in the “space of reasons”, where it can stand as reasonable or unreasonable depending on the reasons we cite for holding it. If we can have reasons for belief that are distinct from the causes of those beliefs, it would seem that the existence of sufficient physical causes for our beliefs does not stand in the way of our ability to recognize them as justified on the basis of reasons. 

However, the suggestion that reasons provide a special sort of non-causal explanation faces a serious difficulty: If reasons are non-causal in the sense described above, then forming a belief for certain reasons cannot provide any basis for thinking that what we believe is actually true. If I believe that P for some good reason, Q, the truth of my belief will only be guaranteed if Q actually obtains. But if I do not take Q to be what causes my belief that P, then the fact that it is my reason for believing that P does not put me in a position to know whether anything at all ensures the truth of my belief that P. Lewis himself makes a similar point:

“...even if [non-causal] grounds do exist, what have they got to do with the actual occurrence of belief as a psychological event? If it is an event it must be caused. It must in fact be simply one link in a causal chain which stretches back to the beginning and forward to the end of time. How could such a trifle as lack of logical grounds prevent the belief’s occurrence and how could the existence of grounds promote it?” (Lewis 1978, p. 16. Brackets added)

For all I know, Q may be my reason for belief even though, in fact, it is not the case that Q. Consequently, knowing that I believe that P because of some good (non-causal) reason, Q, will not put me in any position to recognize whether my belief is true or false. If reasons are going to serve as explanations that put us in a position to recognize the truth of our beliefs, then they must be facts that cause us to form beliefs as a rational response to what is actually the case. 

In light of the considerations above, we should conclude that “reasons explanations” are some sort of causal explanation. If the mind is a physical organ, then reasons must be causes that affect that physical organ in a way that leads to the production of beliefs. However, this proposal is in tension with the claim that we recognize reasons as what cause our beliefs as well as what ensure their truth. In short, we cannot simultaneously hold that the mind is physical and that our beliefs have genuinely rational explanations. If the mind is a physical organ, then the causal relations that obtain between our beliefs and the facts that cause them are determined by the laws of nature that govern our universe. In other words, when certain facts cause a belief to be formed, this will result from the physical character of those facts, the physical character of the mental organ (along with our beliefs), and the laws of nature that determine how things with those physical characteristics interact with one another. However, if this is the case, then there is no basis for supposing that the same facts that cause my beliefs also ensure their truth. Assuming that the mind is a physical organ, is perfectly coherent to suppose that our beliefs are caused by facts that have no relation at all to the things we form beliefs about. Even if it just so happened that our beliefs were caused by facts that ensured their truth, the mere awareness that our beliefs were caused in a certain way would still not enable us to actually arrive at a judgment concerning their truth. In order to recognize our beliefs as true, there must be some evident and essential connection between the causes of our beliefs and the facts that those beliefs are about. But this connection is precisely what we must reject insofar as we hold to the view that the mind is a physical organ. We must reject it because the causes of physical entities are fully determined by their physical characteristics and the laws of nature, not by the intentional content of our beliefs or principles of logical consequence.

We are now in a position to give a precise account of why rational explanations of belief are incompatible with other forms of causal explanation: In order to have genuinely rational explanations that can establish the truth of the beliefs that they explain, there must be an evident and essential connection between the facts that explain our beliefs and the facts that ensure the reality of whatever our beliefs are about. However, as shown above, if the mind is a physical organ that is susceptible to non-rational forms of causal explanation, then there can be no evident and essential connection of this sort. Consequently, insofar as we take our beliefs to have sufficient non-rational explanations, we cannot also hold that they are rationally explained. 

Since our beliefs do have rational explanations in terms of reasons that ensure their truth, what should we conclude about the nature of the mind? As this discussion suggests, it cannot be any physical organ. Rather, the reality of reason itself establishes the immateriality of mind and judgment. Insofar as the mind is non-physical, it is not governed by physical laws and the causal relations that they entail. The principles of thought are rational principles that guarantee an essential connection between the causes of our beliefs and their truth. We acknowledge the reality of these principles whenever we recognize the truth of our beliefs in light of the reasons that explain them. The implications of this acknowledgement preclude a purely physical account of the mind and vindicate C.S. Lewis’s belief in a “cardinal difficulty” facing naturalism.  

Addendum: 

1. It is sometimes suggested that C.S. Lewis’s argument from reason has been improved upon and/or superseded by more sophisticated attempts to show that naturalism is self-defeating. Specifically, Alvin Plantinga’s evolutionary argument against naturalism has occasionally been held up as such an innovation. Without attempting to refute Plantinga’s argument in detail, it is worth highlighting a key advantage of Lewis’s approach: Plantinga’s argument depends upon a controversial premise concerning the prior probability of reliable cognitive faculties, given naturalism and evolution. By contrast, Lewis requires no such assumption. Even if the prior probability of reliable cognitive faculties was high given naturalism and evolution, Lewis’s argument could still succeed. This is because Lewis attacks the very possibility of rational explanations on naturalism rather than their probability. 

2. The immaterial mind is governed by rational principles that ensure an essential connection between the explanations of our beliefs and their truth. However, there are clearly cases of false belief and beliefs that are not formed for good reasons. How can the possibility of such cases be explained on this account? Although, in normal conditions, the mind will be caused to form true beliefs for good reasons, exceptional cases of malfunctioning remain possible. When someone forms a false belief or forms a belief without good reasons, these must be explained in terms of a non-rational cause. This will involve some sort of interference, where the mind is acted upon by some external, non-rational cause instead of acting in accordance with its own rational principles. This may seem to present a skeptical threat: If we cannot distinguish between cases in which our mind is acting in accordance with rational principles and cases in which it is being interfered with, how can we be confident that our reasons for some belief actually ensure its truth? The general response to arguments from illusion will also apply in this case. Our inability to recognize when we are reasoning unsuccessfully does not entail that we lack conclusive evidence when we are reasoning well. When we are reasoning well, we know that our beliefs are explained by reasons that ensure their truth. Consequently, even though we are unable to recognize when we are reasoning unsuccessfully, beliefs formed by reasoning well are not subject to doubt. 

3. Physicalists may attempt to argue that they can establish a connection between the causes of our beliefs and their truth by appealing to natural selection. Natural selection, they might claim, allows us to account for why our rational faculties successfully track the truth. This may seem to provide grounds for affirming a physicalist account of rational explanation. The difficulty facing any proposal of this sort is simple: These accounts can only explain why our beliefs are generally correlated with the facts that make them true. They do nothing to undermine the key contention that, if the mind is a physical organ, there is no essential connection between the causes and the truth of our beliefs. Furthermore, the absence of this essential connection prevents the physicalist from consistently recognizing the truth of their belief that natural selection favors cognitive reliability in the first place. Because it fails to establish the essential connection required for rational explanation, this evolutionary proposal provides no distinctive advantage for the physicalist. 

Epistemology’s False Dichotomy

 Consider the following quote by William Hasker: 

“Epistemo­logical externalism has its greatest plausibility in cases where the warrant for our beliefs depends crucially on matters not accessible to reflection­, for instance, on the proper functioning of our sensory capacities. Rational inference, in contrast, is the paradigmatic example of a situation in which the factors relevant to warrant are accessible to reflection; for this reason, examples based on rational insight have always formed the prime ex­amples for internalist epistemologies.”

Hasker’s comment highlights a key distinction between internalism and externalism in epistemology. For many internalists, warrant must be something that is subjectively available to the believer. It is something the believer can reflect upon and that allows them to make sense of why they form the beliefs that they do (and why they are right to do so). By contrast, for many externalists, a belief can be warranted whether or not a subject is able to recognize or reflect upon what warrants their belief. 

Insofar as these positions are understood as competing views about the conditions under which beliefs are warranted, their merits can be straightforwardly compared with one another. However, it is not clear to me that this is how we should understand these positions. 

Consider Descartes’s reflections on doubt. When Descartes realized that, for all he could subjectively establish, many of his beliefs might have been false, he was plagued by doubt. This sent him in search of a method that would enable him to overcome his doubt and rest his beliefs on a secure foundation. In Descartes’s case, what was at issue was not whether his beliefs were warranted or not. For all he knew, his beliefs may very well have been warranted if externalism is true. Rather, Descartes wondered how he could possibly maintain his beliefs in light of his inability to subjectively establish their truth. It would be of no benefit to Descartes to suggest that his beliefs might be warranted by being the results of reliable cognitive faculties. If we cannot maintain beliefs in the absence of subjectively accessible warrant, the possibility of inaccessible warrant won’t provide any assistance in the Cartesian struggle against doubt. 

In my opinion, the case of Descartes provides a key insight into the debate between internalists and externalists in epistemology: The reason why internalists see externalism as a non-starter is because, unless the warrant for one’s beliefs is subjectively accessible, one will not be able to maintain those beliefs at all. Insofar as a subject realizes that they cannot recognize any basis for thinking that their beliefs are true, they will simply refrain from holding those beliefs. This truth, according to internalists, is self-evident upon reflection to any rational thinker.

In light of this internalist position, the externalist insistence on the possibility of subjectively inaccessible warrant is worthless as a response to reflective doubt. The internalist basis for rejecting externalism is not simply the fact that externalist standards for warrant are too low. Rather, it is the fact externalist standards for warrant apply to beliefs that are not possible to maintain upon reflection. The disagreement between internalists and externalists is not about the conditions under which a belief has some commonly agreed upon status called “warrant”. Internalists are concerned with warrant in the sense that subjects can have upon reflection and externalists are not. To this extent, internalists and externalists are talking past one another. 

Addendum: 

Externalists often oppose this kind of internalist position on the grounds that our judgements simply have to bottom out in beliefs that lack subjectively accessible warrant. According to these externalists, perceptual judgements and other basic beliefs cannot be formed on the basis of further subjectively accessible reasons. Consequently, unless we wish to deny the possibility of perceptual judgements that can withstand rational reflection, we must accept the that beliefs can be maintained with subjectively inaccessible warrant.

However, this worry rests on the assumption that beliefs are the only source of subjectively accessible warrant. Internalists can reject this assumption and recognize perceptual experiences, in addition to beliefs, as conceptual states capable of providing subjectively accessible warrant. This enables the internalist to insist that subjectively accessible warrant is necessary for maintaining beliefs upon reflection while also recognizing the possibility of basic beliefs.

An argument from reason against mind-body physicalism

When one believes something on the basis of certain reasons, one takes those reasons to explain why one’s belief is true. For example, if I believe that Socrates is a mortal because all men are mortal and Socrates is a man, I do not simply think that my belief is causally explained by those reasons. Rather, I also take those reasons, insofar as they are the causes of my belief, to explain why my belief that Socrates is a mortal is true. If I did not take those reasons to explain why my belief that Socrates is a mortal is true, I would not believe that Socrates is a mortal at all. 

If the same reasons that cause my beliefs also explain why my beliefs are true, then the content of my beliefs cannot depend on anything other than the character of the reasons that cause them. If they depended on anything further, then the fact that certain reasons caused my beliefs would not also be sufficient to explain the truth of those beliefs. Instead, an explanation of the truth of my beliefs would depend upon the nature of the further factor that influenced the content of my beliefs in addition to the reasons that caused me to form them. This would prevent me from from ever recognizing my beliefs as true by recognizing my reasons for forming them. 

If mind-body physicalism is true, then our beliefs are physical phenomena that are governed by the laws of nature and that stand in causal relations with other physical phenomena. These laws determine the causal relations that obtain between our beliefs and the causes that explain them. Furthermore, these laws are not sensitive to rational relations of implication or entailment. If this is the case, then the truth of our beliefs does not simply depend on the causes of those beliefs. Rather, it also depends on the natural laws of our universe. Specifically, it depends on whether the natural laws of our universe entail causal relations that ensure the truth of beliefs that are caused by the appropriate reasons. This is precisely the kind of further factor that prevents a subject from ever recognizing their beliefs as true on the basis of their reasons for forming them. In order to know whether my beliefs were true, in this case, I would first have to determine whether the laws of nature were of the appropriate sort. But any belief about the laws of nature would itself have to be recognized as true on the basis of the reasons that explained it. This is impossible unless I already take the contents of my beliefs to be explained solely in terms of the character of the reasons that cause them. Consequently, a belief in mind-body physicalism precludes the rational possibility of recognizing the truth of our beliefs, including our belief in mind-body physicalism.

In short, if the reasons that cause our beliefs also explain their truth, then the contents of our beliefs do not depend on anything other than the character of the reasons that cause them. But if mind-body physicalism is true, then the contents of our beliefs do depend on something other than the character of the reasons that cause them. So if mind-body physicalism is true, then it is not the case that the reasons that cause our beliefs also explain their truth. The truth of this last consequent is incompatible with the possibility of rational warrant for one’s beliefs. Therefore, mind-body physicalism is incompatible with rational warrant for one’s beliefs, including one’s belief in mind-body physicalism.

Addendum:

While the argument above is an objection to mind-body physicalism alone, related (though more controversial) considerations will also apply to anti-physicalist alternatives. 

If the mind is a physical or a non-physical substance, then there will necessarily be some truths that it cannot know. In particular, it will be incapable of knowing its own nature precisely because the truth of any belief that a mind has about its own nature will depend upon that nature itself. In order to know that the reasons that cause my beliefs also explain their truth, I must have some understanding of the nature of belief and the mind. In particular, I must know that beliefs are such as to be caused by reasons that ensure their truth. But this knowledge is precisely what is unavailable to me insofar as the mind is a physical or non-physical substance. I have no basis for trusting any belief that I form about the nature of a mental substance because the recognition of any trustworthy basis would depend upon knowledge of the very mental nature that I am trying to grasp. If I believe that a mental substance normally forms true beliefs, I can only trust this judgment insofar as I know that my beliefs are responsive to reality. But this is precisely what I need to establish in the first place. 

I can only know the nature of my mind insofar as I know that this nature is simply what i think it to be. Insofar as it is anything other than what I think it to be, its nature lies beyond me and I cannot know that beliefs are such as to be responsive to objective reality. I do not know the mind to be a physical or a non-physical substance in thought. I do not know it to be any substance at all. Therefore, if the mind is a physical or a non-physical substance, I cannot know its nature and I cannot know my beliefs to be warranted. But I do know my beliefs to be warranted because I know that the mind is no physical or non-physical substance.

Comments On Physicalism And Vagueness

- Comment 1:

Some philosophers have suggested that our difficulties with conceiving of borderline cases of consciousness stem from our temptation to accept a paradoxical demand. Specifically, when we try to conceive of a borderline case of consciousness, they claim that we try to conceive of what it would be like to be in such a state. However, if there is something it is like to be in a certain state, that state just is a determinate case of consciousness. So, according to this proposal, we are trying to conceive of a borderline case of consciousness in a way that prevents us from actually doing so, whether or not they are possible. But this proposal mischaracterizes the relevant situation. When we attempt to conceive of a borderline case of consciousness, we try to imagine a relation to (or a state that is related to) a borderline case of phenomenal character. This is not an attempt to conceive of a borderline case of consciousness in terms of what it is like. Therefore, the attempt does not present any paradoxical demand. On a related note, it may be true that, if we were in such a borderline state, we would not be able to determinately recognize it as such (because we would not be clearly conscious). But one can surely recognize the character of a state that one conceives of, even if one could not recognize the character of that state while the state was actually occurring.

- Comment 2:

According to some philosophers, in order to competently grasp a given concept, we must be able to conceive of determinate cases where the referent of that concept is present or absent and, if the concept is vague, borderline cases as well. Since we seem to be unable to conceive of relevant borderline cases for our Consciousness concept (which we seem to competently grasp), should we conclude that consciousness is sharp? I don’t think so. Consider the case of the concept Life. In the past, when people took our Life concept to be sharp, it is plausible to suppose that they would not take any conceivable situation to involve a borderline case of life. However, it seems wrong to suggest that they did not competently grasp the relevant concept (if there is, in fact, such a thing as competence with respect to our “grasp” of concepts). Rather, these past subjects simply came to make discoveries about the nature of life that led them to realize that borderline cases of life are possible. Their prior inability to recognize borderline cases of life was caused by false beliefs about life, not conceptual incompetence. We could similarly imagine a subject who came to hold strange beliefs about the sufficient conditions for life that specified sharp boundaries for its presence. It seems that this subject would also take borderline cases of life to be inconceivable. Nevertheless, despite their strange beliefs, there is no reason to suppose that the subject would lack conceptual competence instead of simply having misleading beliefs. Consequently, we should deny that conceptual competence with vague concepts implies an ability to conceive of relevant borderline cases (or at least cases that one would recognize as borderline).


- Comment 3:

Normally, if a concept is vague, we can conceive of situations in which a borderline case of its referent is present. What explains why this is true? Without offering a general account, the following hypothesis suggests itself: When we have a competent grasp of a given empirical concept, we can conceive of the sorts of situations in which the evidence that leads us to apply that concept is present. If an empirical concept is vague, it will normally be the case that the evidence that leads us to apply that concept can come in greater or lesser degrees. Consequently, if we competently grasp a vague empirical concept, we should normally be able to conceive of a situation in which the relevant evidence is present to such a degree that we recognize a borderline case of that concept’s referent. This proposal provides a satisfying explanation of why we view the inconceivability of borderline cases as evidence for their metaphysical impossibility: If we can conceive of the sorts of situations in which the evidence that leads us to apply a vague empirical concept is present, in most if not all cases, that evidence will come in greater or lesser degrees. So if we are unable to conceive of such evidence in greater or lesser degrees that would lead us to recognize a borderline case, this is a defeasible reason to conclude that the concept is sharp. However, this principle runs into trouble when we consider the case of consciousness.

When we conceive of conscious experiences, we apply our Consciousness concept on the basis of the phenomenal character of our experience. Crucially, we do not use this concept to refer to the phenomenal character of our experience. Rather, when we recognize the phenomenal character of our experience, this is our evidential basis for concluding that we are having some kind of conscious experience. In this sense, our introspective judgments about consciousness are displaced insofar as they are made on the basis of something we are conscious of rather than an awareness of consciousness itself. Unlike ordinary cases, however, it is not obvious that we should expect this evidential basis to come in greater or lesser degrees. For example, suppose that strong property representationalism is true. In this case, the phenomenal character of an experience will be an abstract property complex that the experience represents. Can an abstract property complex be present in greater or lesser degrees? It is hard to even make sense of this suggestion. First, a property complex is an abstract object, so the degree to which it is present cannot vary between situations. Second, abstract objects are plausibly fundamental in a sense that precludes being present to a certain degree at all. Perhaps it could be argued that, when there is a borderline case of the representation relation, an experience only makes a property complex somewhat present for the subject. In this scenario, it might be claimed, we have a borderline case of a property complex. However, a borderline presentation of a property complex does not entail any presentation of a borderline property complex. As argued above, there are no possible borderline property complexes to be presented. Consequently, according to at least one theory of phenomenal character, we should not expect our evidential basis for applying our Consciousness concept to come in greater or lesser degrees. Most importantly, this would be true even if borderline cases of consciousness are, in fact, possible. Because the absence of variation by degrees in our evidential basis for applying our Consciousness concept does not imply that consciousness itself is sharp, our inability to conceive of situations where we recognize a borderline case of consciousness is not a good reason to conclude that borderline cases of consciousness are metaphysically impossible.

- Comment 4:

According to the explanatory proposal offered above for the conceivability of borderline cases, when we competently grasp a vague concept, we should normally be able to conceive of situations in which our evidence for applying that concept is present in greater or lesser degrees. According to many non-representationalist theories of consciousness defended by contemporary physicalists, our Phenomenal Character concept is vague. Consequently, these proposals suggest that we should be able to conceive of situations where our evidence for phenomenal character is present to greater or lesser degrees. Tye, Antony, and others have persuasively argued that this is not the case. Furthermore, unlike in the case of consciousness, the absence of variation by degrees in our evidential basis for applying our Phenomenal Character concept is not compatible with its being vague. This is because, if we apply our Phenomenal Character concept on the basis of our direct acquaintance with phenomenal character itself (or some underlying physical property) and phenomenal character admits borderline cases, we should be able to imagine situations where our evidence establishes the presence of phenomenal character to a greater or lesser extent. Therefore, if we endorse the explanatory proposal described above, we should conclude that phenomenal character is sharp and reject any physicalist proposal that suggests otherwise (this would include the views proposed by David Papineau and Ned Block among others). As noted previously, this implication does not threaten strong property representationalism.

Conceivability, Zombies, And Vagueness

Among philosophers, it is often suggested that there is some link between conceivability and metaphysical possibility. Most commonly, this suggestion takes the form of the following principle: If P is conceivable, then P is metaphysically possible. This principle is sometimes qualified so as to specify that the link in question is defeasible. In other words, if P is conceivable, this provides defeasible evidence for the claim that P is metaphysically possible. 

A stronger form of this alleged link between conceivability and possibility has been proposed along the following lines: If P is conceivable, then P is metaphysically possible. Furthermore, if P is not conceivable, then P is metaphysically impossible. The latter half of this stronger principle can also be qualified in terms of defeasible evidence.

These principles underlie two key arguments against physicalism in the philosophy of mind:

1. It is conceivable that all of the actual physical facts obtain in the absence of any mental facts.

2. If it is conceivable that all of the actual physical facts obtain in the absence of any mental facts, then it is possible that all of the actual physical facts obtain in the absence of any mental facts.

3. Therefore, it is possible that all of the actual physical facts obtain in the absence of any mental facts.

This is the so-called “zombie argument” against physicalism. 

The second argument runs as follows:

1. If mental states/properties are physical states/properties, then it is possible that there are borderline cases of mental states/properties.

2. It is inconceivable that there are borderline cases of mental states/properties.

3. If it is inconceivable that there are borderline cases of mental states/properties, then it is not possible that there are borderline cases of mental states/properties.

4. Therefore, it is not possible that there are borderline cases of mental states/properties.

5. Therefore, mental states/properties are not physical states/properties. 

This is the so-called “vagueness argument” against physicalism. 

Premise 2 of the zombie argument and premise 3 of the vagueness argument are both supported by the conceivability principles described above. Consequently, in order to evaluate these arguments, we should evaluate the conceivability principles that support them. 

Turning first to the weaker conceivability principle, one potential motivation for accepting that conceivability is evidence for metaphysical possibility is its intuitive plausibility. It seems to us that what we conceive of being the case is what is metaphysically possible. However, how should we understand problematic cases such as the apparent conceivability of a world where water is not composed of H20 (it has been persuasively argued by Saul Kripke that such a world is metaphysically impossible)? In such cases, Kripke and others have suggested, what we really take to be conceivable is a world where some watery stuff is not composed of H20, rather than a world where water is not composed of H20. Consequently, the apparent contingency of water’s identity with H20 can be explained away in terms of a world where the contingent properties we normally associate with water are not instantiated by H20. According to this explanation, conceivability is a genuine guide to metaphysical possibility and metaphysically impossible worlds are inconceivable. 

However, what explains why we take certain possibilities to be conceivable at all? Without offering a general account, the following hypothesis suggests itself: When we normally apply two empirical concepts on the basis of independent evidence (where the evidence that leads us to apply one concept is not necessarily associated with evidence that leads us to apply the other concept in the same situation), we can conceive (or take ourselves to conceive) of a world in which the evidence that leads us to apply one concept is present in the absence of the evidence that leads us to apply the other. For example, since our H20 concept is applied on the basis of H20’s presence while our water concept is applied on the basis of some watery stuff’s presence, we can conceive of a world where some watery stuff is present in the absence of H20. Likewise I can conceive of a world where a journalist at the Daily Planet is present in the absence of a flying superhero with a red cape. This latter case gives rise to the apparent contingency of Clark Kent’s identity with Superman. 

The hypothesis described above provides a satisfying explanation for why we take conceivability to be a guide to metaphysical possibility: If the evidence that leads us to apply one empirical concept is necessarily associated with the evidence that leads us to apply another concept, in most cases, we will apply both concepts in the same epistemic situations. Consequently, if we recognize that we do not apply both concepts in the same epistemic situations, this is a good reason to conclude that their referents are only contingently correlated. However, this principle runs into trouble when we consider the case of mind-brain identity. 

When we apply our C-fiber concept and our pain concept, we do so on the basis of different evidence. We apply our C-fiber concept on the basis of the presence of C-fibers. By contrast, we apply our pain concept, directly, on the basis of our experience of pain and, indirectly, on the basis of the behavior of other organisms. According to the hypothesis under consideration, this will entail that we can conceive of a world where pain is present in the absence of C-fibers. But unlike ordinary cases where we apply our empirical concepts, our C-fiber and Pain concepts are applied on the basis of two radically distinct forms of epistemic access to reality. Specifically, our Pain concept is applied on the basis of direct experiential acquaintance while our C-fiber concept is not. For this reason, even if the evidential bases for applying these concepts were necessarily associated, we would still not expect them to be applied in the same situation. This is because, in one situation, we may be directly acquainted with pain without being in a situation where we would apply our C-fiber concept. Likewise, we could be in a situation where we would apply our C-fiber concept without being directly acquainted with pain. Because such cases are possible, the fact that we do not apply our Pain and C-fiber concepts in all of the same situations is not a good reason to conclude that their referents are only contingently correlated. Consequently, if the hypothesis presented above is accepted, we have a good reason for rejecting premise 2 of the zombie argument. 

Turning now to the stronger conceivability principle, one motivation for accepting that inconceivability is a guide to the metaphysical impossibility of borderline cases is the simply fact that, normally, if a concept is vague, we can conceive of situations in which a relevant borderline case of its referent is present. What explains why this is true? Without offering a general account, the following hypothesis suggests itself: When we have a competent grasp of a given empirical concept, we can conceive of the sorts of situations in which the evidence that leads us to apply that concept is present. If an empirical concept is vague, it will normally be the case that the evidence that leads us to apply that concept can come in greater or lesser degrees. Consequently, if we competently grasp a vague empirical concept, we should be able to conceive of a situation in which the relevant evidence is present to such a degree that we recognize a borderline case of that concept’s referent. 

The hypothesis described above provides a satisfying explanation of why we take the inconceivability of borderline cases as evidence for their metaphysical impossibility: If we can conceive of the sorts of situations in which the evidence that leads us to apply a vague empirical concept is present, in most cases, we will be able to conceive of situations in which that evidence is present to greater or lesser degrees. If we are unable to do so, this is a good reason to conclude that a given concept is sharp. However, this principle runs into trouble when we consider the case of consciousness. 

When we conceive of conscious experiences, we apply our “Consciousness” concept on the basis of the phenomenal character of our experience. Crucially, we do not use this concept to refer to the phenomenal character of our experience. Rather, when we recognize the phenomenal character of our experience, this is our evidential basis for concluding that we are having a kind of conscious experience. Unlike ordinary cases where we apply empirical concepts, however, it is not obvious that we should expect this evidential basis to come in greater or lesser degrees. For example, suppose that strong representationalism is true. In this case, the phenomenal character of an experience would be an abstract property complex that the experience represents. Can an abstract property complex be present to greater or lesser degrees? It is hard to even make sense of this suggestion. First, a property complex is an abstract object, so the degree to which it is present cannot vary between situations. Second, abstract objects are plausibly fundamental in a sense that precludes being present to a certain degree at all. Consequently, according to at least one theory of phenomenal character, our evidential basis for applying our Consciousness concept will not come in greater or lesser degrees. Most importantly, this could be true even if borderline cases of consciousness are, in fact, possible. Because the sharpness of our evidential basis for applying our Consciousness concept does not imply that consciousness itself is sharp, our inability to conceive of situations where we recognize a borderline case of consciousness is not a good reason to conclude that borderline cases of consciousness are metaphysically impossible. Consequently, if the hypothesis presented above is accepted, we should reject premise 3 of the vagueness argument against physicalism. 

In this post, I have provided two hypotheses that aim to explain when and why we are able to conceive of certain situations being actual. I have argued that, if these hypotheses are accepted, we have good reasons for rejecting key premises that occur in the zombie and vagueness arguments against physicalism. Whether these hypotheses are ultimately endorsed will depend upon wider considerations relating to modal epistemic theorizing, but they strike me as plausible and explanatorily powerful. For this reason, I believe physicalists have firm grounds for rejecting the zombie and vagueness arguments against physicalism.

Addendum:

According to the second explanatory hypotheses presented above, when we competently grasp a vague empirical concept, we should normally be able to conceive of situations in which our evidence for applying that concept is present in greater or lesser degrees. According to many non-representationalist theories of consciousness defended by physicalists, our Phenomenal Character concept is vague. Consequently, this hypothesis implies that we should be able to conceive of situations where phenomenal character is present to greater or lesser degrees. Tye, Antony, and others have persuasively argued that this is not the case. Furthermore, unlike the case of consciousness, a sharp evidential basis for applying our Phenomenal Character concept is not compatible with its being vague. This is because, if we apply our Phenomenal Character concept on the basis of our direct acquaintance with phenomenal character itself and phenomenal character admits of borderline cases, we should be able to imagine situations where the relevant evidence is present to greater or lesser degrees. Therefore, if we endorse the hypothesis under consideration, we should conclude that phenomenal character is sharp and reject any physicalist proposal that suggests otherwise (this would include the views proposed by David Papineau and Ned Block among others).