Perception and “illusion” with Dr. Louise Moody

by Daniel A. Kaufman

I talk with Dr. Louise Moody about perception, “illusion style” arguments, and J.L. Austin.

Louise has a PhD in philosophy and is an independent philosopher and feminist campaigner.

[Note: There are points at which Louise’s mic cuts out for a second, but it does not substantially interfere with watching the discussion.]

1:30 Opening sketch of philosophy and perception / Descartes and “illusion-style” arguments / “Indirect Realism” / Skepticism. 3:45 Louise: There is a logical gap between illusions, hallucinations and other such phenomena and the metaphysical and skeptical conclusions people have based on them. 12:00 Louise: We really ought to distinguish between illusions and hallucinations, when engaging in these inquiries. For one thing, illusions are public in a way that hallucinations aren’t. 19:12 Naïve Realism, the “vulgar” view of perception / The primary-secondary quality distinction / Berkeley and Kant. 33:05 Austin on “material object.” 37:00 Louise on “material object.”


4 responses to “Perception and “illusion” with Dr. Louise Moody”

  1. I thought this was a pretty good discussion. And I agree that illusions are different from hallucinations.

    I usually find philosopher’s discussion of perception to be strange. For example, there’s that discussion of the “bent stick illusion”. I don’t see that as an illusion. If the stick were to look straight, rather than bent, that would seem more of an illusion. But seeing it as bent is just the way that light refracts, so should not be considered an illusion.

    Discussions of hallucination always seem abstract to me. It might make more sense to talk of dreams. Or, better still, we all have the experience of watching a movie on the big screen and being absorbed into the plot.

  2. I agree that the bent stick is not an illusion; it is what is actually seen due to refraction of light.

    In general, I am wary of the very notion of “illusions”. Can perception be an illusion? I would call it “a local fact” or a “local truth.”

    To claim that what someone perceives is an illusion implies that for a person who perceives it differently it is “the real thing”, the objective truth of what is there. Is a mirage on the asphalt on a hot day real? For a person not seeing water, it would be the other person’s illusion. It’s not a matter of whether there is actually water on the road, but whether the perception of water is real for the perceiver.

  3. Animal Symbolicum

    Two other things about illusion — related to its publicity — that skeptics tend to ignore in their arguments:

    (1) Something counts as illusory for us only if something else counts as nonillusory. There are many ways of making this point. For one, it’s not that the stick appeared to be bent when it seemed as though it were placed in what seemed to be water; it’s that the stick appeared to be bent when placed in water. For another, if it’s granted that the stick only seemed to be bent, then it’s granted that the stick was not bent: if we go so far as to count something as illusion, we have already granted that it is not real (or whatever term you prefer), meaning we have already granted that something is real (ditto). For yet another, there’s the Nietzschean thought that if everything is illusory, nothing is, since illusoriness is significant only if contrast-able with nonillusoriness.

    (2) Perceptual illusions are designed to exploit skilled perceptual systems: only well-working perceptual systems can be tricked. (This doesn’t mean that all visual systems, for example, can be tricked with the same illusions.) What defines a well-working or skilled perceptual system? One answer (among other controversial ones, of course) is that it is good at keeping us out of trouble with reality. So, according to this view, we must already be fairly well-attuned to the nonillusory to be tricked into taking the illusory as nonillusory.

    None of these considerations refutes the brand of skepticism in question. But I think they place significant pressure on such skepticism.

    As an aside, I’ll add that, mutatis mutandis, similar considerations apply to those who would draw provocative, cocktail-party conclusions about our irrationality: something counts as irrational only against a broad background of rationality (Davidson was good on this), and only broadly rational systems can be susceptible to irrationality — or, patterns of irrationality are signs of a broadly well-functioning rationality (Kant was one of the first to discuss this).

  4. Sorry to be a bit late, but I’ve been busy. Did want to say, I listened to this conversation, and really liked it; we’ve been talking a lot about social issues here, which can wear on one, and this was a welcome visit into more traditional philosophic concerns.

    On a side note, I don’t know if the regressions that come in the gradual development of dementia can really be considered illusory or hallucinatory, since what is going on is the withering of brain cells themselves thus reducing the neurological capacity for functional perception/ recognition of immediate context; which suggests that there is some term or conceptual dimension not yet discussed here.

    (If I have more time soon, I’ll try to elaborate further.)