May 29, 2010

Can Immediate Perception Save Realism? (Hint: No)

As I mentioned in my last post, now that the term is over I am catching up on some stuff I've been meaning to read. Another item on that list is Georges Dicker's "Anti-Berkeley" which appeared in British Journal for the History of Philosophy in 2008. Dicker's aim is to show that many of Berkeley's arguments are good, but immaterialism, nevertheless, does not follow. Dicker thinks that Berkeley's arguments are best seen as showing us how to formulate a better version of materialism than the one common in Berkeley's day. So, for instance, Dicker thinks that Berkeley successfully refutes the substratum theory and materialists should therefore be bundle theorists.

My concern here is with the second argument Dicker considers, the argument against representationalism. Dicker formulates the argument as follows:

(1) Whatever is perceived by the senses is immediately perceived (PPI).
(2) Only ideas are immediately perceived.
(3) Only ideas are perceived by the senses. [from (1) and (2)]
(4) No material things are perceived by the senses. [from (3)] (p. 342)

Dicker suggests that PPI is true under only one interpretation of immediacy, namely, the absence of conscious inference. But in this sense, according to Dicker, (2) is false. What Dicker doesn't realize is that Berkeley actually has an argument for (2) with this interpretation of immediacy. (This is closely related to the line of thought I considered in my post on How Reductive Theories of Mental Representation Lead to Phenomenalism.) Here's the argument (I'm too lazy to look up references right now; it's all in the New Theory of Vision somewhere):
  1. All immediate (in Dicker's sense) perception is (to anachronistically borrow some terminology from Reid) either original or acquired.

  2. The only objects of original perception are ideas.

  3. In acquired perception, one is able to perceive an object of type t1 (e.g. Joe's embarrassment) by perceiving an object of type t2 (e.g. Joe's blushing) because one has learned to associate objects of type t1 with objects of type t2. (In Berkeley's terminology, objects of type t1 come to suggest objects of type t2.)

  4. In order to learn to associate objects of type t1 with objects of type t2, one must already be able to perceive objects of both types.

  5. Therefore,
  6. Acquired perception cannot allow us to perceive any object types not already perceivable by original perception. (From (1), (3), and (4))

  7. Therefore,
  8. The only objects of acquired perception are ideas. (From (2) and (5))

  9. Therefore,
  10. The only objects of perception are ideas. (From (1), (2), and (6))

A couple of notes on the example of acquired perception in (3) (the example is Berkeley's), and then I'll discuss the plausibility of the premises. First, note that Berkeley uses the term 'idea' extremely broadly. I take it that he believes that embarrassment is not merely represented by an idea, but is an idea (as are other emotions, etc.). Second, while we can't have acquired perception of mind-independent objects, we can have acquired perception of ideas in other minds (though not the minds themselves). This is because I can learn to correlate blushing with embarrassment in myself, and then apply this to others. Thus acquired perception can allow us to perceive individual objects (e.g. someone else's embarrassment) that we could never perceive originally, but it can't get us any new object types.

Now, how plausible are the premises? (1) can be safely stipulated if we take 'acquired' to mean 'learned' and 'original' to mean 'not learned'. (3) seems like a pretty plausible model for how we would learn to perceive things, and (4) seems like a pretty plausible constraint on that process. The premise open to question is (2). But this means that in order to save realism it is not enough to say, as Dicker does, that we perceive mind-independent objects without making a conscious inference; one must go on to say that this is innate.

This doesn't necessarily undermine Dicker's general thesis: one can still maintain that present-day materialists can avoid Berkeley's arguments. But this does have the consequence that Berkeley has brought more of the Lockean edifice crashing down than Dicker seems inclined to recognize. The argument points to serious problems with the combination of empiricism, realism, and the 'way of ideas.' Berkeley, being strongly committed to empiricism and the 'way of ideas', quite sensibly decided that realism had to go.

Posted by Kenny at May 29, 2010 2:04 PM
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What is the Problem with Empiricism, Realism, and the Way of Ideas?
Excerpt: After discussing my last post offline with Lewis yesterday, I wanted to clarify this claim: "The argument points to serious problems with the combination of empiricism, realism, and the 'way of ideas.'" The problems I have in mind are difficulties with...
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