In ‘Criteria, Defeasability, and Knowledge’, McDowell presents the argument from illusion has follows:
“In a deceptive case, what is embraced within the scope of experience is an appearance that such-and-such is the case, falling short of the fact: a mere appearance. So what is experienced in a non-deceptive case is a mere appearance too. The upshot is that even in the non-deceptive cases we have to picture something that falls short of the fact ascertained, at best defeasibly connected with it, as interposing itself between the experiencing subject and the fact itself.” (386)
This is fairly closely connected to the version of the argument from illusion we discussed last time, which we laid out like this:
| 1. | All experiences have an object (the relational view of perception). |
| 2. | Hallucinatory experiences do not have objects which are external to the mind. |
| 3. | Hallucinatory experiences have objects which are internal to the mind. (1 & 2) |
| 4. | The objects of experience are the same in the case of hallucinatory and veridical experience. |
| C. | The objects of all experiences, whether hallucinatory or veridical, are internal to the mind. (3 & 4) |
The language is somewhat different; rather than talking about objects internal to the mind, McDowell talks about ‘mere appearances.’ But this difference does not appear to be crucial. And McDowell does not make explicit the claim that all experiences have an object; but he does talk about ‘what is experienced’, which seems to come to the same thing.
McDowell raises a series of objections against the view that we always experience ‘mere appearances’ which are similar to some of the objections we discussed last time against sense datum theory. He argues that knowledge of external objects would have to be via inference from those appearances, that it is plausible to think that such inferences would have to underwritten by knowledge of a theory connecting appearances and external things, but that it is hard to see how we could so much as understand such a theory without perceptual acquaintance with anything other than appearances.
Rather than going along with the conclusion of the argument from illusion, he suggests the following response:
“But suppose we say -- not at all unnaturally -- that an appearance that such and such is the case can be either a mere appearance or the fact that such and such is the case making itself perceptually manifest to someone. As before, the object of experience in the deceptive cases is a mere appearance. But we are not to accept that in the non-deceptive cases too the object of experience is a mere appearance, and hence something that falls short of the fact itself. ...So appearances are no longer conceived as in general intervening between the experiencing subject and the world.” (386-7)
In the context of the above presentation of the argument from illusion, this amounts to denying premise (4).
McDowell considers an argument against disjunctivism which is not dissimilar to the arguments from Ayer which we discussed last time:
“The most obvious attraction [of anti-disjunctivist views] is the phenomenological argument: the occurrence of deceptive cases is experientially indistinguishable from non-deceptive cases.” (389)
But McDowell thinks that this argument is ‘inconclusive’, since the disjunctivist can allow that in deceptive cases the object of perception is genuinely an appearance that things are thus-and-so, which naturally will be indistinguishable from the fact that things are thus-and-so.
Why you might think that this is not enough by way of response to this argument: the need for an account of what appearances are, that they can be indistinguishable from facts.
The second main objection that McDowell considers is less a direct objection to the denial of premise (4) of the argument from illusion than it is an argument that disjunctivism cannot do the epistemological work that McDowell thinks that it can, and so that the disjunctivist is in the same epistemological boat as the sense datum theorist. He puts the objection like this:
“...a mere appearance can be indistinguishable from what you describe as a fact made manifest. So in a given case one cannot tell for certain whether what confronts one is one or the other of those. How, then, can there be a difference in what is given in experience, in any sense that could matter to epistemology?” (389-90)
The assumption which underwrites this objection: facts which do not make a difference to ‘how it seems’ to an agent cannot affect one’s epistemic standing.
A reply to the argument, based on detaching the intuition behind internalism from the demand for certainty.
McDowell seems to think that all experiences have objects; so it seems that he takes seriously the idea that there are such things as appearances. But, in this piece at least, we get little idea of what sorts of things these appearances are supposed to be. Sometimes, as when discussing the views of ‘common kind’ theorists, he seems to use ‘appearance’ as one might naturally use ‘sense datum’; so perhaps he thinks that in hallucinations one is aware of sense data. This is a question which Martin takes up in his paper.
McDowell writes as though all perceptual experiences are neatly classifiable as illusory or veridical. But the standard case is surely one in which an experience has some veridical and some illusory aspects. Should we then think that the experience has several objects, some of them facts and some of them appearances? McDowell does not say; but it is not clear that there is a natural answer to this question from within his framework.
Another assumption which seems to be at work in McDowell’s argument is that any non-disjunctivist ‘highest common factor’ view of the objects of experience will be something akin to sense datum theory. This is an assumption which we’ll find reason to question next week when we read Johnston’s paper.