Friday, 29 December 2006

J-Reliabilism and the New Evil Genius

In this post, I outline what has come to be known as the New Evil Genius objection to reliabilism. There are several versions of reliabilism currently available, but the one I have in mind has to do with justification and amounts the following claim:
(J-Rel) For any agent S, S’s belief that p is justified IFF it was formed via a reliable process (i.e., a process that tends to produce true beliefs).
The following claim seems to be in keeping with our common sense intuitions about justification:
(NEG) The extent to which S is justified in believing that p at time t is the same as the extent to which S’s recently envatted duplicate is justified in believing that p at t.
However, the combination of both (NEG) and (J-Rel) leads to the following implausible conclusion:
(C) The beliefs of S’s recently envatted duplicate are produced by reliable processes.
To see this, let us begin by simplifying (J-Rel) and (NEG) for the purpose of argumentation. First, we may note that (J-Rel) entails (A):
(A) If S’s belief that p is justified, then it was produced by a reliable process.
Likewise, we may simplify (NEG) by noting that in cases where S’s belief that p is justified, (NEG) entails (B):
(B) (Recently envatted) S’s belief that p is justified.
From premises (A) and (B) we can construct an argument for the conclusion (C), as follows:

(A) If S’s belief that p is justified, then it was produced by a reliable process.

(B) (Recently envatted) S’s belief that p is justified.
Therefore, by modus ponens:
(C) (Recently envatted) S’s belief that p was produced by a reliable process.
But (C) is intuitively false. For those given to logical minutia, the proof for the denial of (J-Rel) from the above premises would look something like this:
  1. ~(C) {premise (ex hypothesi)}

  1. {(A) . (B)} → (C) {premise (restatement of (Arg1) above)}

  1. (NEG) → (B) {premise (as defined above)}

  1. (J-Rel) → (A) {premise (as defined above)}

  1. (NEG) {premise (common sense intuition)}

  1. ~{(A) . (B)} {from (i) and (ii), by modus tollens}

  1. {~(A) V ~(B)} {from (vi), by De Morgan’s laws}

  1. (B) {from (iii) and (v), by modus ponens}

  1. ~(A) {from (vii) and (viii), by disjunctive syllogism}}

  1. ~(J-Rel) {from (iv) and (ix), by modus tollens}

Saturday, 16 December 2006

Looking for a Causal Criterion for Vision

Below, I attempt to derive (what may be described as) the standard causal criterion for vision [see (3)*** below] from a critical examination of a non-causal definition of vision. By so doing I hope to make explicit some of the motivating intuitions that lie behind the causal account. The non-causal definition of vision with which I will like to begin may be schematically expressed as follows:

S sees an object O before him only if
(1) S has an experience E such that it looks just as if O is before him
(2) There is an object O before S
However, this definition hardly seems sufficient for saying that S sees O before him. For example, we may construct something akin to a Gettier-type counterexample to (1) and (2). (I say that the following example is merely ‘akin’ to a Gettier case because unlike the genuine Gettier counter-example mine is not concerned with the question of justification.) Imagine S has his eyes closed and is hallucinating that there is an object O before him. Suppose further that there actually is an object O before him. In such a case, the requirements of both (1) and (2) have been met, and yet we would not wish to say that S sees O before him since S would continue to have the experience E even if O was not present. This observation has motivated a causal account of perception that stipulates that S only counts as seeing O if E is caused by O. Thus we arrive at:
(3) S’s experience E is caused by O.
As it stands, the stipulation that E is caused by O does not seem sufficient since we can imagine instances when such causal dependence holds but in which we would still not count S as seeing O. Grice presents us with two such scenarios [Grice 1961, 141-5]. The first case is where S has his eyes closed and another person, P, describes the object O to S, which then prompts S to have a hallucination of O. In such a case, S’s experience E is caused by O, albeit indirectly via P’s description. Since E is ultimately causally dependent on O, the demands of (3) have been met. Yet, we would still be unwilling to say that in such a scenario S sees O. Thus, as it stands, the addition of (3) is still not sufficient for defining a case of vision.

One possible reply to Grice’s first example would be to point out that it is highly unlikely that P’s description of O could give rise to a hallucination in S that perfectly matched O. Thus, if we added a clause to (3) requiring that E perfectly match O we would (it is supposed) exclude cases of hallucinations based on the description of an object. Thus we arrive at something like:
(3)* S’s experience E is caused by O and E perfectly matches O.
At least three points can be made with regards to the above reply to Grice’s first example. First, it is not clear that it is impossible for P to describe O in enough detail for S to have a hallucination of O that fulfilled the requirement of (3)*. Admittedly, this may be difficult to do depending on how complex O happens to be, but it certainly isn’t (strictly speaking) impossible. In fact, it may even turn out that the perfect match between E and O may simply be a matter of luck, this would still be sufficient to fulfill the requirement of (3)*, so long as E is (indirectly) caused by O. Moreover, we could imagine a case in which O is a simple geometric shape such as a triangle or square. In such a case it wouldn’t seem all that difficult for P to describe O in such a way that S’s hallucination of O perfectly matched O.

Second, (3)* does not seem like a plausible necessary condition for vision since there are many cases in which we may be willing to say that S sees O although E does not perfectly match O. For example, let us suppose that S sees a white shaggy dog, which he mistakes for a sheep. In such a case, S’s experience E may not perfectly match O and yet it is not clear that we would wish to deny that S sees O. Other examples include misreading the letters (or words) on a street sign and certain cases of blurred vision. Moreover, there is at least one reading of ‘perfectly matches’ in which it wouldn’t make sense to say any experience E perfectly matches (or in any way matches) O. On such a reading experiences may be taken to be a very different kind of thing from the objects that give rise to them. While I’m not particularly keen on pushing for such an interpretation of experience vis-à-vis objects, it does seem to be a viable position one may hold.

Our third and final objection to (3)* comes from Grice’s second counterexample. Grice imagines a scientist who looks at an object O and stimulates S’s brain in exactly the way necessary for S to have an experience E that matches O. If instead of a scientist we substituted a sophisticated computer, then the possibility of E perfectly matching O perfectly (at least as perfect as we could reasonably expect in a normal case of vision) becomes quite plausible. Given this fact, along with the fact that E remains causally dependent on O, the demands of (3)* have once again been met. Nevertheless, we would still be unwilling to say that in such a scenario S sees O. Thus, the addition of (3)* still leaves us with an insufficient causal criterion for vision.

Another way one may object to Grice’s examples is by pointing out that in both the causal dependence of E on O is indirect. If we stipulate that the causal dependence must be direct we arrive at:
(3)** S’s experience E is caused by O directly.
The word ‘directly’, as used in (3)** suggests that there cannot be any mediating factors between O and E. However, this does not seem like a plausible requirement for vision since there are cases where O may cause E indirectly where we would nevertheless still wish to insist that S sees O. For example, imagine that S is looking at bacteria on a slide with the aid of a powerful microscope. In such a case, E’s causal dependence on O is mediated (i.e., by the microscope) and yet we may still wish to insist that S sees O.

Although the requirement that O directly cause E seems problematic, it does hint at a valuable intuition: namely, that there are a number of possible causal scenarios linking E to O that would be unacceptable as far as our putative understanding of vision is concerned. According to this line of reasoning our concept of vision includes the notion that there should be a certain type of causal relationship between perceptual experiences and their objects. Thus, for S to see O, his perceptual experiences must be caused in the right sort of way, where this is understood as excluding all causal chains that deviate from ‘the norm’. What constitutes ‘the norm’ can be arrived at easily enough by examining unproblematic instances (i.e., paradigm cases) where the locution ‘S sees O’ correctly applies. Examples, such as Grice’s discussed above, represent causal chains that deviate from the norm and therefore fail to be causally relevant in the right way. If we add the requirement excluding deviant causal chains to (3) we arrive at:
(3)*** S’s experience E is caused by O in the right sort of way.
Admittedly, what the expression ‘right sort of way’ entails needs to be spelt on in greater detail. Nevertheless, (3)*** is regarded by many to reflect the canonical statement of the causal requirement of vision and is taken, along with (1) and (2) to be sufficient for establishing that S sees O.

The causal criterion we have derived represents merely the first step, rather than the end, of the debate regarding whether the causal description of vision is the best available. For example, many believe disjunctivism represents an attractive alternative to the causal picture, though it remains unclear whether the two approaches are necessarily incompatible. Moreover, while (1), (2) and (3)*** are here taken to be sufficient for vision, another question worth considering is whether they also represent a necessary condition.

Friday, 8 December 2006

Greco's Argument that McDowell is an Externalist

In his essay ‘Externalism and Skepticism’, John Greco insists that pace all his lip-service to the Sellarsian idea of the “space of reasons”, McDowell is an out and out epistemic externalist. Greco maintains that McDowell’s externalist leanings become obvious upon a careful examination of his disjunctivist reply to scepticism. Greco accepts McDowell’s disjunctivist claims as they stand but points out that we cannot tell whether we are in the good (veridical) case or bad (non-veridical) case via introspection alone. Given this fact, we must conclude that what gives us knowledge in the good case is itself not introspectively available.

Given my McDowellian sympathies, I didn’t initially find Greco’s arguments very compelling. However, while I still maintain it would be a gross oversimplification to call McDowell an epistemic externalist (or an epistemic internalist for that matter), I can sympathize with the intuitions that prompted Greco’s pronouncement. The crux of Greco’s argument is that McDowell’s content externalism (CE) implies epistemic internalism (EE), the thesis that one need not have introspective access to the basis of one’s justification. McDowell advocates (CE) in order to maintain that in experience we actually take in bits of the world. However, as McDowell appears to acknowledge, part of the price to be paid for his particularly brand of (CE) is the Cartesian notion of transparency of the mental:
One reason, then, to pursue a less restricted conception of object-dependent propositions is the interest of its radically anti-Cartesian implications. In a fully Cartesian picture, the inner life takes place in an autonomous realm, transparent to the introspective awareness of its subject; the access of subjectivity to the rest of the world becomes correspondingly problematic, in a way that has familiar manifestations in the mainstream of post-Cartesian epistemology. If we let there be quasi-Russellian singular propositions about, say, ordinary perceptible objects among the contents of inner space, we can no longer be regarding inner space as a locus of configurations which are self-standing, not beholden to external conditions; and there is now no question of a gulf, which it might be the task of philosophy to try to bridge, or declare unbridgeable, between the realm of subjectivity and the world of ordinary objects. We can make this vivid by saying…that objects themselves can figure in thoughts which are among the contents of the mind. (McDowell (1986): 145-6. Italics his)
What McDowell seems to offer us, then, is a trade-off. We can hold on to the Cartesian notion of the complete transparency of the mental, but doing so would keep the mental cut off from the world and, by all appearances, void of empirical content. On the other hand, we may embrace the idea of the objects themselves figuring in our mental contents, but doing so will cost us the notion of complete transparency of the mental. In sum, to the extent that objects in the external world figure among our mental content, to that extent our mental content is rendered opaque to us.

By “opaque”, I mean that there are parts of our mental content that we do not have introspective access to. The upshot of this fact in the context of McDowell’s disjunctivism quickly becomes apparent. In the non-veridical case there is something missing (namely, the object which figures among our mental content in the good case). But that ‘something missing’ is the very thing that is rendered opaque in the context of McDowell’s content externalism. This explains why we can be in the bad case without knowing that we are in the bad case. Since that which is present in the good case and missing in the bad case is opaque (i.e., introspectively inaccessible), then there is no way for us to even know if and when it (i.e., the object which is making itself perceptually manifest) is missing. The upshot of this is that what differentiates between the good and bad case is not something we can discover by introspection. What I take to be Greco’s point, then, is that what makes the good case good—that is, what gives us knowledge—is itself opaque, which is to say introspectively inaccessible. But introspective inaccessibility to what gives us knowledge just is (EE). It would seem therefore, that McDowell’s version of (CE) entails (EE).

Saturday, 2 December 2006

Welcome to the Space of Reasons

‘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’. - Wilfrid Sellars

John McDowell’s account of perceptual knowledge is arguably one of the most innovative presently available. However, one risk that often accompanies being innovative is that it is sometimes difficult to see how one’s ideas relate to more traditional lines of thought. If this is true of any analytic philosopher, it is true of McDowell, who is often taken by undergraduate philosophy majors and seasoned practitioners alike as a paradigm case of philosophical obfuscation. Moreover, the terminology and ideas that make up the usual stock and trade of epistemology—e.g., justification, epistemic internalism, content externalism, Twin Earth examples—are seldom explicitly employed or discussed by McDowell. Instead, he tends to resort to obscure metaphors and cryptic locutions; such as ‘the logical space of reasons’, ‘the interpenetration of inner and outer’ and ‘frictionless spinning in the void’. Unfortunately, this has prompted many to dismiss McDowell as irrelevant to the central concerns of epistemology. This blog represents my attempt to help remedy this problem. By discussing McDowell in relation to more traditional philosophical concepts, theories and theorists, I hope to make explicit, motivate and clarify, what I take to be central themes of McDowell’s epistemological project.