What’s the big deal about illusions?

By Luis Favela

Before I begin my final post as a Featured Early-Career Author here on The Philosophers’ Cocoon, I’d like to again thank Marcus for providing a forum for people like me to share our work in a safe and fun environment. Thanks, Marcus! Now, to the post:

In this final post, I will attempt to persuade you to think that visual illusions are not a big deal, where “big deal” means “special” and “mysterious.” From Joni Mitchell to Cypress Hill, illusions have been a topic of great interest to many artists. In addition to folk singers and rappers, philosophers have also been very interested in illusions, especially visual illusions. I think the mystery of illusions often results from either a mislabeling of the phenomenon or misattributing properties to a phenomenon. Mislabeling occurs when, for example, somebody says, “I'm having illusions driving me mad inside.” In this case, they are actually thinking of hallucinations and not illusions. Hallucination, as I’m defining the term, refers to the internal phenomenal experience of a single mind. For example, somebody with schizophrenia who hears voices could experience an audio hallucination, or somebody under the influence of hallucinogens who sees a giant pink elephant in their dining room would be experiencing a visual hallucination. In this way, hallucinations are “internal.”

Illusions, as I’m defining the term, refer to experiences tied to how the external world is. One example is the straight stick that looks bent in water. This is an example of the second reason I mentioned above as to why illusions are mysterious, namely, the misattribution of properties. In the case of visual illusions, the properties that are often misattributed are those that are involved in hallucinations. For example, misattribution occurs when whatever properties are involved in the experience of seeing a pink elephant in your dining room when you’re under the influence of hallucinogens (perhaps those involved with imagination?) are appealed to as either causally related to or constitutive of the experience had in a visual illusion. A hallucination of a stick looking bent in water would be caused by the internal states of the experiencer. Seeing a real (i.e., out in the world) straight stick look bent in water is a visual illusion because the experience is caused by states external to the experiencer. In the case of the stick looking bent in water, the “external states” include the way light rays refract at the air-water boundary.

The straight stick looking bent in water is a “big deal” (i.e., special and mysterious) when it is treated as something being perceived incorrectly by the senses; or, when the world could be correctly perceived by the senses. Holding a straight stick in front of your healthy eyes, with clear air, and enough light, but seeing it as bent would likely be a hallucination (e.g., caused by being under the influence of hallucinogens) and would be an incorrect perception. Placing a straight stick in water and looking at it with your healthy eyes, in clear air, and enough light, but seeing it as bent would be an illusion, but it would be a correct perception.

This is why I do not think illusions are a big deal: If the experience is of something weird like a pink elephant in your dining room, then it’s internally caused, incorrect, likely unexpected, and is a hallucination—not an illusion. But if the experience is of something weird like a straight stick looking bent in water, then it’s externally caused, correct, expected, and is an illusion. In the year 2015, there’s nothing particularly special or mysterious about the effects of light refraction on perception.

This is where philosophers of perception—especially disjunctivists—make a mistake by making a “big deal” out of visual illusions. A major issue for a number of disjunctivists is whether or not a perceiver can subjectively discriminate veridical, hallucinatory, and illusory perceptual experiences. Some disjunctivists talk in terms of “seemings.” For example, take the case of somebody walking by a pond and seeing a stick in water that looks bent. As an example of the argument from illusion, this is a case whereby the perceiver thinks an object has a quality that objects of that kind do not normally have; in this case, the stick is really straight but looks bent. There is no reliable way for the perceiver to distinguish between the phenomenal experiences of veridical and illusory perceptions. The bent stick in water can seem to have the same appearance to the perceiver as if the stick were really bent.

This is the wrong way to go about attempting to understand hallucinations and illusions. “Seems” talk leads to the inability to provide empirically adequate accounts of the phenomenal, epistemological, and behavioral features of perception. If seeing a real bent stick in the water and “seeing” an illusory straight stick in the water that looks bent both seem to be the same experience, then perception becomes an issue of explaining how the mind produces images and what the differences, if any, there are between images that correspond to something in the world and those that do not. As John McDowell puts it, thinking of perception in these terms results in “seemings” serving as an epistemological concept grounded solely in the perceiver’s subjective, phenomenological experience; such arguments are inconclusive. “Seemings” do not provide arguments upon which to generate a theory of perception because, taken on their own, they are not compelling sources of evidence.

I don’t think such treatments of perception as disjunctivism are going to give satisfying accounts of illusions. In contrast, along with the ecological psychology tradition, I think that perception is best treated as direct. In this way, the properties of the environment play very important roles in perceptions, such that “illusions” are externally caused, correct (i.e., specified), and expected. “Of course the straight stick looks bent in water, that’s what happens when you look at something passing through the air and water. What would you expect?” Hallucinations—such as those involving visual imagery—are a whole other story. But maybe, just maybe, you don’t think illusions are such a big deal anymore.

Thanks for reading!

Comments

[Sean Enda Power]

Hi Luis,

Thanks for the very interesting post. I agree with the general sentiment, although I think that I hold that, if there Are illusions, then they are a big deal. They are a big deal because, since how things seem is Not how things are, then we cannot trust how things seem.

However, I think I disagree on a few of your points.

(a) In my above statement, I am taking it that, if we cannot trust seemings (or appearances, as I prefer it), then this is a problem. One reason it might be a problem is that one wants to take seemings as evidence. You put that aside, and note lots of people of do. However, why put seemings aside?

Here's one reason: because there are illusions. Illusions give us reason to hold that we cannot trust how things seem.

In that case, if we reject the 'big deal' of illusions, then we lose reason to distrust seemings.

I think that we can't trust seemings is a problem -- at least for naive realists, but also I think for anyone trying to ground their epistemology in experience (e.g., as some foundationalists might, including one reformed coherentist, BonJour). I take it that, although seemings may not always be sufficient as evidence, they are necessary for evidence.

Further, if one's theory, in most cases, saves the seemings, then this is a good-making feature of the theory. It is a reason to pick it over alternative theories which do not save this way (of course, such a theory may be rejected for lots of other reasons).

I also assume it is not a bad-making feature of a theory if it has (a) any account of seemings and (b) does not have an account of erroneous seemings -- such as illusions or hallucinations. That is, I think we should try save the appearances but we have no obligation to do so erroneous appearances.

This is why I appreciate the desire to get rid of illusions, to make them no big deal. However, I'm not sure your approach is enough.

(b) I think that, if you are reject illusions, it isn't enough to point out that there are well-developed physical theories, e.g., of optics. Given there are illusions (or hallucinations) in the first place, and seemings are unreliable, that we have a physical theory of how they come about won't eliminate them. It will just be a physical explanation of how they come about. What is needed to save the seemings (again, my motivation, not yours) is an account in which the seemings correspond to how things are.

Does that happen with bent sticks in water, mirages, and so on? My thinking is you might be able to develop some account by going back to the Berkeley-ian arguments regarding the relationship between how things 'look' (i.e., seem) and how things are.

E.g., what is the correct way for a stick in water to LOOK so that it appears as it really is? Or: what is the correct way for an island over the horizon to LOOK so that it appears as it really is?

My thought here is it might do more than eliminate the need to talk of illusions as mysterious or problematic. It might also rehabilitate seemings/appearances.

[Louie Favela]

Hi Sean,

Thanks for taking the time to comment on my post. I am sympathetic to a lot of what you’re saying. I don’t think this will alleviate much of your concerns, but upon retrospect, I think I should have titled my post: How to not make illusions a big deal for direct perception. At the core of a lot of what I said was an attempt to motivate the claim that illusions need not be a big deal for theories of direct perception. Moreover, those disjunctivists of the direct perception persuasion are going about it wrong. With that said, let me respond to some of your other points.

I mostly agree with your point that a well-developed theory of visual perception can give a physical account of illusions, but will not do much to account for the phenomenal experience of said illusion. I think we both agree that the physical account makes illusions not a “big deal” in the sense that we know why they are experienced as they are (e.g., light refraction at the air-water boundary in the case of the stick in water), and knowing why makes them less mysterious.

What I want to get away from is appearance/reality distinctions in matters of perception. I think that’s where a lot of our disagreement lies. “Sure, we have a physical account of how the stick looks bent in water, which could explain why the sense data seems the way it does. But it’s still an illusion—i.e., a big deal—because the appearances (“seeming”) are not revealing of the reality.” I guess I want to skip around the point and respond in a deflationary kind of way: “Well, if perception is direct, then the appearance is the reality. As a source of visual perception, it doesn’t just seem to be bent, but the stick really is bent in water.” Moreover, if the stick were to serve as a source of other kinds of perception, then those need to be involved as well, which would change the nature of the perception. For example, if the stick will be engaged with visually and haptically, then grabbing the stick, manipulating it, and placing it in and out of water will reveal that the stick—as a source of combined visual and haptic perception—is straight.

This is a very systems-based approach to perception, and is inspired by the ecological psychology approach to perception, which says that all perception requires taking into account that the organism-environment is a single system, where the features of the environment and capacities of the organism constrain what is perceived, and where perception and action are inextricably connected. In this way, perhaps we can save “seemings” if we allow that perceptual appearances are the reality—that is, until more perceptual information is available; and at that time the appearances will change, as will the reality.