I’m pleased to introduce our second Ergo symposium, featuring Boyd Millar’s “Naïve Realism and Illusion” with commentaries by Craig French (Cambridge) and James Genone (Rutgers). Thanks to each of the participants for their excellent work and to John Schwenkler for helping me put the symposium together.
According to naïve realism, perceptual experience consists in a subject’s conscious acquaintance with ordinary objects and properties of the environment. According to its proponents, only naïve realism can accommodate introspective evidence about the phenomenal character of perception as well as the explanatory role experience plays in an adequate account of empirical knowledge.
According to Millar, though, we should reject naïve realism, because it cannot accommodate illusion. If you look at a circular object through a special shape-distorting lens, e.g., the object will look elliptical to you. This is an example of illusion: you see the object and some of its properties (e.g., colour, distance), but misperceive at least one of its properties (e.g., its shape). Millar proceeds by considering the different ways naïve realists have tried to explain illusions and showing why each way is unsustainable.
Millar begins by considering disjunctivism about illusion. Disjunctivism holds, roughly, that veridical and non-veridical experiences are not mental states of the same type. A naïve realist adopting disjunctivism about illusions proposes that, whereas veridical perception consists in acquaintance with how things are, illusions consist in something else altogether.
Millar’s argument against the disjunctivist proposal has two steps: first, he argues that naïve realists should allow that illusions at least partly consist in acquaintance with perceived objects and properties, since the same considerations that favour naïve realism for purely veridical perception also favour naïve realism for the veridical aspects of illusion; second, he argues that if illusion at least partly consists in acquaintance, then, given the interdependence of phenomenal features, it must wholly consist in acquaintance. Disjunctivism about illusion is therefore unavailable to naïve realists.
Next, Millar considers two non-disjunctivist naïve realist proposals about illusion. According to the first proposal, in an illusion you are prevented from perceiving properties you would normally perceive and judge that the object has some property which it lacks. Looking at the circular object through a shape-distorting lens, e.g., you are prevented from experiencing shape and mistakenly judge the object to be elliptical. Error enters here only with judgment, not with experience.
Millar objects to this proposal by again invoking phenomenal interdependence. If colour phenomenology depends on shape phenomenology (and vice versa), then you cannot experience an object’s colour while failing to have any experience of shape. Consequently, when you see the circular object through the shape-distorting lens, your experience must (contrary to the above proposal) possess some shape phenomenology.
The second non-disjunctivist proposal attempts to satisfy the above requirement by appealing to an object’s look, understood as a visible mind-independent property of the object. In illusion, the perceived object has a look which is typical of a kind to which the object doesn’t itself belong. Seen through a shape-distorting lens, e.g., circular things have a look characteristic of elliptical things.
Millar offers two reasons to reject this proposal. First, he suggests there is no plausible account of what looks are that would allow them to fulfill the various explanatory roles naïve realism demands of them. Second, even if such an account can be provided, it won’t be sufficient to explain illusions. When you look at a tilted penny, e.g., you experience a look typical of elliptical things. Because of perceptual constancy, though, you don’t misperceive the penny as being elliptical. So, non-paradigmatic looks cannot explain illusion.
You can find the target article, commentaries, and Millar’s response below.
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