Empiricism And The Locus Of Fallibility

John Mcdowell has argued that we can understand much of what has occurred in modern philosophy as responses to a certain sort of philosophical anxiety that is expressed by the question: “How is empirical content so much as possible?” According to Mcdowell, the anxiety results from our temptation to accept two opposing thoughts: “first, that empirical content depends on answerability to impressions, and, second, that impressions could not be the kind of thing to which something could be answerable…” He claims that we are tempted to accept the latter thought because we view impressions as “a natural phenomenon.” If empirical content cannot be answerable to a natural phenomenon, then we cannot make sense of how empirical content is answerable to impressions so long as we assume that impressions are a sort of natural phenomenon. 

In Mcdowell’s work, he attempts to overcome this philosophical anxiety but providing an account of impressions that empirical content can be answerable to. He attempts to do this showing how our temptation to accept the second thought, that impressions could not be answerable to a natural phenomenon, rests on an unwarranted conception of nature. Specifically, it depends on our modern assumption that nature is a realm that lies beyond the “space of reasons”. When we recognize that nature exists within that space, he argues, we can recognize how it is possible for empirical content to be answerable to impressions, understood as a natural phenomenon. 

In my view, Mcdowell is right to identify a modern temptation to think that empirical content cannot be answerable to impressions. However, I think it is wrong to suppose that this temptation rests on an assumption that such content cannot be answerable to a natural phenomenon. Instead, I will argue that our resistance towards the notion of answerability to impressions is the result of a mistaken assimilation of indefeasibility and infallibility. In particular, the reason why we are tempted to think that empirical content cannot be answerable to impressions is because we assume that one cannot have indefeasible warrant without having infallible warrant. Because sensory impressions are not an infallible source of warrant, this assumption requires us to deny that they are sources of indefeasible warrant. In the absence of a recognized source of indefeasible warrant, we are led to the philosophical anxiety that Mcdowell describes. I will begin by describing how the assimilation of indefeasible and infallible warrant gives rise to what Mcdowell characterizes as an intellectual “oscillation” between coherentism and the myth of the given. I will then argue that this oscillation can only be overcome through an understanding of how it is possible to have indefeasible warrant without infallible warrant. 

1. Infallibility And The Sensory Given 

The appeal of modern philosophical empiricism stems from our conviction that knowledge about the natural world must be answerable to experience. When we reflect on our judgements about reality, the possibility of being satisfied with our beliefs, rather than abandoning them as unwarranted, depends on the possibility of arriving at a satisfying understanding of why we hold the beliefs that we do, in fact, hold. Throughout the history of modern philosophy, it has often been supposed that such an understanding could not be achieved as long as our beliefs were understood to rest upon a fallible basis. If our beliefs about the natural world are fallible, it is tempting to conclude that they might, for all we know, be wrong. After all, we could easily be led to an indistinguishable epistemic situation by an evil demon who is deceiving our senses. In such a case, although it would seem like we were experiencing genuine reality, we would be mistaken. But if this is possible, how can we be confident that we are not being deceived by our senses right now? Surely, many have supposed, we might be wrong when we take things to really be as they seem. 

If sensory deception is possible, then taking one’s beliefs about the world to be based on how the world actually is does not ensure that they aren’t mistaken. In other words, our empirical judgements rest on a fallible basis. But if this is the case, how can we satisfy ourselves that what we believe is true? This question has led many philosophers to conclude that our empirical judgements must not be ultimately based on worldly facts that we can be deceived about. Instead, they have suggested, our empirical judgements have a different, infallible basis: Sense-Data. 

Sense-data, according to empiricists, are an infallible basis for our empirical judgements because we cannot be mistaken when we take ourselves to be aware of them. Because they are an infallible source of knowledge, we cannot be deceived about them in the ways we might be deceived about the worldly facts of common sense. For this reason, we can satisfy ourselves that our beliefs based upon them are ensured to be true. In other words, they are an indefeasible basis for empirical knowledge.

The plausibility of this response to philosophical doubt was called into question by Wilfred Sellars, who described sense-data as a manifestation of the “myth of the given”. According to Sellars, the myth of the given is a pervasive form of philosophical error. In its sensory form, this myth is characterized in terms of an inconsistent triad: 

A. x senses red sense content s entails x non-inferentially knows that s

is red.

B. The ability to sense sense contents is unacquired.

C. The ability to know facts of the form x is ø is acquired.

Empiricists who posit sense-data as an infallible basis of empirical knowledge are committed to endorsing this inconsistent triad because, if they abandon any of its claims, they are denying the features that enabled sense-data to serve as an infallible basis of knowledge in the first place. 

If they abandon A, then they must ultimately deny that sensing sense-data is a basis for our empirical knowledge. However, if they abandon B, then they must ultimately deny that our knowledge of sense-data is infallible (Abandoning C has generally been viewed as a non-option). This is because, insofar as judgments about sense-data depend on acquiring the conceptual capacities associated with our general body of knowledge, they will not be entirely determined by the way things actually are with respect to those sense-data. Rather, what we think about our sense-data will depend, at least in part, on the concepts that we have learned to apply and the ways we have learned to apply them. But if that were the case, how could we satisfy ourselves that we had learned to apply the appropriate concepts in an accurate way? If we believe that the ability to know facts of the form x is ø is acquired, we have introduced the very sort of fallibility into our judgements about sense-data that they were supposed to avoid. 

The myth of the given, in its sensory form, highlights the error of supposing that we can avoid fallibility in our empirical judgements by positing a basis that is immune to cases of illusion or hallucination. The fallibility of our empirical judgments does not result from the possibility of sensory deception alone. It also results from the fallibility of the conceptual capacities that we employ in forming sensory judgements. The myth of the given is the mythic belief in a basis of empirical knowledge that is simultaneously indefeasible and infallible. 

Because sense-data are revealed to be untenable by reflecting upon the myth of the given, some philosophers have become convinced that we must abandon the thought that empirical judgements have a basis in objective reality. This is the “coherentism” that Mcdowell is keen to reject. According to this sort of coherentism, our judgements about the natural world are not answerable to that world at all. In other words, we must abandon our attempts to understand empirical judgments as beliefs based on how things actually stand (even if the coherentist can hold that most of our empirical beliefs will inevitably be true). But this position is just as unacceptable as a commitment to the myth of the given. If we cannot satisfy ourselves that our beliefs about the world are based on how things stand, then we cannot recognize any reason for thinking that things actually are as we believe them to be. We can imagine a person in this sort of predicament as one who might proclaim “Sure, I believe that there is a red car in the parking lot, but for all I know, it might be blue or there may be no car in the parking lot at all!” But a person who lacked commitment to the reality of a red car in this way would not be a person who believed in a red car in any serious sense at all. Their judgement about the red car would simply dissolve in the light of critical reflection upon their reasons for belief. The problem with coherentism is not that it fails to explain why our beliefs count as knowledge. Instead, the problem is that it fails to explain why our beliefs count as beliefs. The person who accepts coherentism is a person who does not take on any reflectively robust commitments about how things actually stand in mind-independent reality. While such a person might be said to have beliefs in a sense that is of interest to cognitive science or psychology, they do not have the sort of beliefs that modern philosophy has sought to preserve and justify since its inception.

2. Infallibility And Indefeasibility 

The flight to coherentism is brought about by a conviction that experience cannot provide us with an appropriate basis for our empirical judgment. This conviction, in turn, stems from the thought that an appropriate basis for empirical judgements must be infallible. In this section, I will argue that this thought is the fundamental mistaken assumption that gives rise to the philosophical anxiety identified by John Mcdowell. 

The idea that our basis for empirical knowledge must be infallible can seem persuasive at first. If we could be in an indistinguishable epistemic situation and still be wrong in our beliefs, then it is difficult to see how our epistemic situation in cases of veridical perception could ever be sufficient to ensure that our beliefs about the world are true. The key assumption, shared by philosophers who credit this apparent difficulty, is that an epistemic situation is something that we can always recognize as such. If this assumption is granted, then cases of indistinguishable illusions or hallucinations must involve the same sort of epistemic situation that obtains in cases of veridical experience. Consequently, our evidence in veridical cases of experience cannot be different from our evidence in non-veridical cases. Since our evidence in non-veridical cases of experience fails to establish that things actually are as they seem, this assumption entails that our evidence in veridical cases fails in this way as well. In other words, our basis for empirical judgements about mind-independent reality must not be indefeasible. 

However, as Mcdowell has famously argued, it is a mistake to assume that we are always in a position to recognize the evidence that is available to us. It is perfectly consistent to suppose that veridical cases of experience provide us with evidence that we do not have when we are subject to illusions or hallucinations. In the latter cases, although we might take ourselves to have indefeasible evidence for our empirical judgements, we are simply mistaken. In contrast, when we form empirical judgements in veridical cases of perception, we have and take ourselves to have indefeasible evidence that conclusively establishes the truth of our beliefs. 

This sort of view might be resisted on the grounds that it does not explain how we are able to satisfy ourselves that our empirical judgements are true. One might wonder, “How can I be certain that I believe there is a red car in the parking lot because there is a red car in the parking lot?” 

But this worry simply commits the same mistake that was already addressed: Just like empirical judgements can be known, in good cases, on an indefeasible basis, so can beliefs about my reasons for judgment. In good cases, when I reflect upon the basis of my empirical knowledge, I know my reasons for belief on the basis of indefeasible evidence. In bad cases, neither my empirical knowledge nor my judgment about my reasons for belief has an indefeasible basis. Even though they are indistinguishable “from the inside”, the good and bad cases are different in this way. 

Modern philosophy has long supposed that our empirical judgements can’t be based on indefeasible evidence because our perceptual judgements are fallible. This supposition, in turn, was the result of a conviction that we must base our beliefs about the world upon an infallible foundation in order to overcome the threat posed by skeptical doubt. But this is a mistake. In the good cases, our fallible cognitive faculties can provide us with indefeasible evidence for our judgements about the world. 

In his work, Mcdowell has sought to diagnose a form of anxiety that results from the characteristic assumptions of modern philosophy. In light of the considerations above, we can, instead, recognize that the assumptions of modern philosophy are themselves a product of anxiety. They result from a felt need to rule out, once and for all, the possibility of forming misguided beliefs about the world. Since this desire cannot be satisfied by fallible cognitive faculties, modern philosophers sought for some alternative, but there is no alternative to be found. Rather than calling our knowledge of the world into question, philosophers should reassess the anxious desire for security at the root of our modern assumptions. 

Sellars And Wittgenstein On Psychological Ascriptions

 

Here are two quotes from Wilfred Sellars and Ludwig Wittgenstein:

“The essential point is that in characterizing an episode or a state as that of

knowing, we are not giving an empirical description of that episode or state; we

are placing it in the logical space of reasons, of justifying and being able to

justify what one says.” - Wilfred Sellars 

“But it is clear that A believes that p, A thinks p, A says p, are of the form “‘p' says p”: And here we have no co-ordination of a fact and an object, but a co-ordination of facts by means of a co-ordination of their objects.” - Ludwig Wittgenstein 

In the quotes above, Sellars and Wittgenstein both suggest that, in our use of certain psychological ascriptions, we are doing something other than providing empirical descriptions of mental states such as “belief” or “knowledge”. According to Wittgenstein, we are “co-ordinating” the elements of one fact (perhaps a fact involving certain signs) with the elements of another fact (perhaps some environmental fact). According to Sellars, we are “placing” an episode or state within the “logical space of reasons”. 

If Sellars and Wittgenstein are correct, then when we say that someone thinks or knows something, we are not placing that subject and their thought within nature. In other words, we are not making a claim about how things are with them and their thought in the way that we might make a claim about, for example, the color of a basketball. Rather, we are assigning a certain normative status to the elements of reality that constitute their assertion or belief in something like the way an umpire might assign a baseball swing a normative status by calling “strike”. 

What makes a view of this sort philosophically interesting is the way it can help to explain the claim that judgement is, in some important sense, self-conscious. 

It has sometimes been said that judgement is self-conscious in the following sense: Thinking “P” is identical to thinking “I think that P”. If judgement is self-conscious, there is no such thing as believing something without, thereby, believing that one believes it. This sort of idea precludes the possibility of a thinker who is, somehow, unaware of what it is that they think. 

But the idea that judgement is self-conscious can be confusing. It certainly seems like the fact that a car is red is different from the fact that I think a car is red. But if this is so, how can my judgement about a car be the same as my judgment about one of my beliefs? This would seem to involve a single belief that is somehow about two distinct facts and that is difficult to understand. In order to address this confusion, we need to unpack how Sellars and Wittgenstein provide a way of seeing how a judgment can be self-conscious without being a judgment about two different facts. 

As noted above, Wittgenstein and Sellars hold that at least some of our psychological ascriptions do not involve empirical descriptions of mental states. Rather, they involve assigning a normative status to certain episodes or objects. If we accept this sort of view, then thinking “P” and “I think that P” does not need to imply that we are thinking about two separate facts. Instead, thinking “P” involves representing the fact that P while thinking “I think that P” involves assigning a normative status to something in the world, by virtue of which, it represents the fact that P. When we recognize that thinking “I think that P” does not require representing a distinct content, we can avoid the confusion associated with self-conscious judgement that was presented above: We can say that the act of representing P is one and the same as the act of assigning a certain normative status to that representation. 

These considerations do not establish that judgment is actually self-conscious. However, they do suggest that one popular source of resistance to that idea can be adequately addressed. 

Comments On “Knowledge And The Internal”

 

In his essay, “Knowledge And The Internal”, John Mcdowell provides a series of theses and optional views that one might affirm about the nature of perceptual knowledge:

Thesis 1 (The Internalist Thesis): We can only reason on the basis of appearances and our rational principles.

Option 1 (The Skeptical View): Reasoning on the basis of appearances and our rational principles cannot result in knowledge of the external world.

Option 2 (The Rationalist View ): Reasoning on the basis of appearances and our rational principles can result in knowledge of the external world all on its own. 

Option 3 (The Hybrid View): Reasoning on the basis of appearances and our rational principles cannot result in knowledge of the external world all on its own, but can result in knowledge of the external world if it produces beliefs that correspond with reality. 

Thesis 2 (The Idealist Thesis): We can reason on the basis of what is the case and rational principles:

Option 1 (The Idealist View): Reasoning on the basis of what is the case and rational principles can result in knowledge of the external world.

According to Mcdowell’s idealist view, appropriate reasons for forming perceptual judgements are located in the external world, rather than in our heads, and perceptual judgements formed on the basis of these reasons can be instances of genuine knowledge. This conclusion does not immediately force us to draw any further conclusions about the nature of perception. In particular, it does not force us to conclude that perceptual states are essentially characterized in terms of representational contents. For all that this paper establishes, there may be a way to understand how perception provides us with reasons of the right sort without involving representational content in any important sense.

In order to move from Mcdowell’s idealist view to a view about perceptual content, we need to identify what sorts of conditions must be satisfied in order for a perceptual judgment to be formed for appropriate reasons. We can begin by providing some remarks about rational belief in general. 

When we form a belief on the basis of certain reasons, this often involves a transition from beliefs that represent those reasons to a belief that represents some conclusion. For example, before John concluded that Socrates is mortal, he first held the beliefs that all men are mortal and that Socrates is a man. These latter beliefs represented his reasons for drawing the conclusion that Socrates is mortal. In this case and many others, it appears that a precondition for believing something on the basis of reasons is the existence of conceptual states that represent the reasons that we are responding to. 

What explains this apparent precondition? One plausible proposal is that, in order to form appropriate beliefs in response to the evidence provided by certain facts, we must have conceptual representations of those facts available for our rational faculties to operate upon. Properly functioning rational faculties are what govern truth-preserving transitions between our cognitive states. They do this by operating upon those states in light of the distinctive conceptual contents that those states possess. Without conceptual representations of our reasons for belief, there would not be any way for the evidence provided by those reasons to make a relevant impact on our belief-forming mechanisms. 

If we accept that conceptual representations of our reasons for belief are a genuine precondition for making judgements on the basis of those reasons, we can then apply this insight to issues involving perception. 

Because of this precondition, perception can only put me in a position to believe on the basis of good reasons if it involves an appropriate conceptual state. The most natural conclusion to draw from this is that perception itself is a conceptual state that represents the reasons it supplies for our beliefs. When I perceive that the car is red, my reason for believing that the car is red is the fact that the car is red. This fact is included in what my perceptual state represents by virtue of its conceptual content. This is why, in accordance with Mcdowell’s idealist view, perception can supply reasons for belief that are nothing other than the worldly facts we are perceiving. 

One might object to the sort of view sketched above by denying that our reasons for belief are ever worldly facts. One might hold, with Donald Davidson, that “nothing can count as a reason for holding a belief except another belief”. If reasons for belief cannot be anything besides other beliefs, perception cannot open us up to reasons that lie beyond our own minds even in principle. 

I think that Davidson’s claim is mistaken. Although other beliefs are required in order for us to *have* reasons for belief, they are not *the same* as those reasons. In an ideal case of reasoning, our beliefs are what enable us to be rationally responsive to worldly facts. It is those facts that serve as our genuine reasons, not the beliefs that represent them. This reflects our common self-understanding of why we believe things. John believes that Socrates is mortal because all men are mortal and Socrates is a man. He does *not* believe that Socrates is mortal because he *believes* that all men are mortal and Socrates is a man. John’s actual reasons are worldly facts that establish the truth of his belief. This is why he presents them to justify his conclusion about Socrates. 

Another possible objection is presented by reasoning based on false beliefs. In cases of perceptual illusion, we seem capable of making justified inferences on the basis of false beliefs about what is in our environment. If we appeal to worldly facts that do not actually exist as our reasons for perceptual judgement, how can there be any justifiable inferences at all in such situations? What distinguishes a rational response to undetectable illusion from an irrational response? 

I think the appropriate thing to say here is that, in these cases, people are mistaken about their reasons for belief. Although someone suffering an illusion might claim that their perceptual beliefs are based on how things are in their environment, this isn’t actually true. Those beliefs are actually explained by an inaccurate perceptual state that represents their environment as being a certain way. Similarly, if Paul falsely believes that John is a scoundrel because all lawyers are scoundrels and John is a lawyer, then, since John is not a lawyer, it is Paul’s *belief* that John is lawyer, rather than the fact, that partially explains his conclusion. When we form judgements based on false beliefs, we are mistaken about what actually explains our judgments. Although we think that our judgements are explained by worldly facts, they are actually explained by our false beliefs. In these sorts of cases, we sometimes say that a person is justified, despite lacking knowledge, because they formed appropriate beliefs on the basis of the evidence as it appeared to them. Justification applies to beliefs that would have been knowledge if the subject had not been undetectably deceived. 

In conclusion, this version of Mcdowell’s idealist view claims that perceptual states represent the external world and supply us with reasons for belief by virtue of their conceptual content. In good cases, perception puts us in touch with what is actually the case and allows us to be rationally influenced by reality. In bad cases, it causally explains our perceptual judgments without producing knowledge. 

Physicalism And Conceivability: Reply To David Pallmann

In a recent facebook post, David Pallman provided the following argument against mind-body physicalism:

“ A modal argument against mind/body physicalism.

1. According to physicalism, I am a physical object/entity.

2. Physical objects/entities cannot possibly exist in the absence of physical things.

3. But I can possibly exist in the absence of physical things.

4. Therefore, I am not a physical object/entity.

5. Therefore, physicalism is false.”

As a reply, I think the physicalist’s best option is to reject premise three by undermining the inference from conceivability to possibility that supports it. In defense of this move, they should, first, provide counterexamples to the claim that positive conceivability entails metaphysical possibility. Second, they should use these examples to motivate an account of conceivability and modal error. Finally, they should argue that, on the basis of this account, anti-physicalist conceivability cases are susceptible to modal error and, thus, unreliable as a guide to metaphysical possibility. Here’s a rough sketch of how that sort of argument might go:

There are possible cases where certain metaphysically impossible situations seem conceivable even after ideal rational reflection. For example, the existence and non-existence of a metaphysically necessary being both seem positively conceivable. However, since one of these cases is metaphysically impossible, at least one metaphysically impossible scenario is positively conceivable. Additionally, it seems positively conceivable that water is composed of H20. However, it is epistemically possible that, in the future, we might discover that we were mistaken and water is actually composed of XYZ. In this situation, what seemed to be positively conceivable (apparently possible, given our knowledge, after ideal rational reflection), would turn out to be metaphysically impossible. This is another possible case where positive conceivability would not be a reliable guide to metaphysical possibility. 

What should we say about conceivability in light of these cases? First, we should give some account of what conceiving of some possibility involves. In my view, the best thing to say is something like this: When we conceive of a possibility, we are describing a total situation in which our worldly evidence is such that we are disposed to judge that certain concepts apply. For instance, when I conceive of a world where water is composed of H20, I describe a world where things with certain functional roles (H20 molecules) realize watery stuff. I am disposed to judge that such a world is one where water is composed of H20, so I take such a world to be possible. However, if I later discovered that water is, in fact, composed of XYZ, then describing such a world (the H20 world) would no longer dispose me to judge that it is one where water is composed of H20. This is because, based on my a posteriori discovery, I would no longer take the relevant worldly evidence (watery stuff) to be actual water. 

The above account suffices as an explanation of why an inference to metaphysical possibility based on conceivability might be defeated by subsequent a posteriori discoveries. However, there are other cases, such as the conceivability of God’s existence and non-existence, that don’t seem capable of being explained in this way. Even if we make the a posteriori discovery that God exists, it seems like we will still be able to describe a total situation in which our worldly evidence disposes us to judge that it is a situation where God does not exist. What these cases show us is that we can describe total situations that, despite being coherent, are nevertheless metaphysically impossible. I think this suggests that positive conceivability is, even in the ideal case, not an indefeasible guide to metaphysical possibility. One lesson we should draw from this is that our judgements about metaphysical possibility cannot be based on conceivability alone. Rather, they must also be informed by the metaphysical implications of a posteriori discoveries as well. 

In light of these considerations, I think what the physicalist should say about anti-physicalist conceivability arguments is that they involve descriptions of coherent total situations containing worldly evidence that dispose us to judge that they are worlds where certain mental phenomena are present in the absence of associated physical phenomena or vice versa. They are ideal cases in the sense that they are not susceptible to defeat by future empirical discoveries because, unlike the case of water and H20, the worldly evidence that disposes us to judge that mentality is present/absent is the existence of mentality itself. When we judge that pain is present, for example, we judge this on the basis of the existence of pain. This is unlike water, where we judge that water is present on the basis of the existence of watery stuff. That is why, even if someone believes that pain is identical to C-fibers firing, they will still find it positively conceivable that pain can exist in the absence of C-fibers. They still find it conceivable because they can describe a total situation where C-fibers are absent but painful sensations are present and, since painful sensations are sufficient for the presence of pain, they will be disposed to judge that this is a world where pain is present but c-fibers are absent. Furthermore, there is no incoherence in our description of a world where pain is present in the absence of C-fibers firing because there are no a priori connections between our concepts of pain (or painful sensations) and C-fibers. As far as a priori reflection is concerned, such a situation is entirely coherent. Nevertheless, based on our a posteriori evidence, the physicalist should say that these concepts both refer to the very same physical phenomenon. Consequently, they should say that the conceivability of anti-physicalist scenarios is not a reliable guide to metaphysical possibility. 

The physicalist can explain the positive conceivability of anti-physicalist scenarios by pointing out that our metal concepts are distinctively “first-personal” in the following sense: We apply them directly on the basis of the phenomena that they refer to. By contrast, our physical concepts are “third-personal” in the sense that we apply them indirectly on the basis of observational evidence. Because these concepts do not have any a priori connections to one another, we cannot infer, a priori, that they co-refer. The possibility of possessing these sorts of co-referring concepts that lack a priori connections can be explained in physicalist terms by appealing to the difference in worldly evidence that disposes us to apply those concepts: We recognize things with certain causal-structural roles as c-fibers and certain phenomenal states of our direct acquaintance as pain. This allows the physicalist to dismiss the positive conceivability of anti-physicalist scenarios an unreliable guide to metaphysical possibility on the grounds that they involve metaphysically impossible descriptions that aren’t recognizable as metaphysically impossible, even after ideal rational reflection. In this sense, they are like the cases where we conceive of the existence and non-existence of God. Anti-physicalist conceivability cases, however, are explained by appealing to the difference in our first-personal and third-personal concepts. 

In summary, the physicalist can provide examples where positive conceivability does not entail metaphysical possibility. These are situations where we describe coherent total situations involving worldly evidence that disposes us to judge that certain facts obtain, even though those situations are metaphysically impossible. The physicalist can then establish that anti-physicalist scenarios depend on descriptions involving worldly evidence that are not a priori incoherent because they appeal to first-personal and third personal concepts that have no a priori connections to one another. Because our a posteriori evidence suggests that mental concepts and physical concepts do, in fact, co-refer, we should conclude that the anti-physicalist scenarios are positively conceivable but metaphysically impossible.  

Addendum: Another lesson that we can draw from these remarks is that conceivability is not the essential tool of metaphysical inquiry that some take it to be. Our modal judgements about metaphysical possibility are determined by more holistic considerations involving a priori reflection, a posteriori discoveries, and abductive theorizing

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.