A few really disastrous mistakes have dominated Western philosophy for the past several centuries. The worst mistake of all is the idea that the universe divides into two kinds of entities, the mental and the physical (mind and body, soul and matter). A related mistake, almost as bad, is in our philosophy of perception. All of the great philosophers of the present era, beginning with Descartes, made the same mistake, and it colored their account of knowledge and indeed their account of pretty much everything. By ‘great philosophers’, I mean Locke, Berkeley, Hume, Descartes, Leibniz, Spinoza, and Kant. I am prepared to throw in Hegel and Mill if people think they are great philosophers too. I called this mistake the “Bad Argument”. Here it is: We never directly perceive objects and states of affairs in the world. All we ever perceive are the perceptual contents of our own mind. These are variously called ‘ideas’ by Descartes, Locke, and Berkeley, ‘impressions’ by Hume, ‘representations’ by Kant, and ‘sense data’ by twentieth century theorists. Most contemporary philosophers think they have avoided the mistake, but I do not think they have. It is just repeated in different versions, especially by a currently fashionable view called ‘Disjunctivism’.

But that leaves us with a more interesting problem: What is the correct account of the relation of perceptual experience and the real world? The key to understanding this relation is to understand the intentionality of perception. ‘Intentionality’ is an ugly word, but we can pretty much make clear what it means; a mental state is intentional if it represents, or is about, objects and states of affairs in the world. So beliefs, hopes, fears, desires are all intentional in this sense. ‘Intending’ in the ordinary sense just names one kind of intentionality, along with beliefs, desires, etc. Such intentional states are representations of how things are in the world or how we would like them to be, etc., and we might say therefore that they have “conditions of satisfaction” — truth conditions in the case of belief, fulfillment conditions in the case of intentions, etc.

The biologically most basic and gutsiest forms of intentionality are those where we don’t have mere representations but direct presentations of objects and states of affairs in the world, and part of intentionality is that these must be causally related to the conditions in the world that they present. Perception and intentional action are direct presentations of their conditions of satisfaction. In the case of perception, the conditions of satisfaction have to cause the perceptual experience. In the case of action, the intention in action has to cause the bodily movement. So the key to understanding perception is to see the special features of the causal presentational intentionality of perception. The tough philosophical question is to state how exactly the character of the visual experience, its phenomenology, determines the conditions of satisfaction.

How then does the intentional content fix the conditions of satisfaction? The first step in the answer is to see that perception is hierarchical. In order to see higher level features, such that an object is my car, I have to see such basic features as color and shape. The key to understanding the intentionality of the basic perceptual experience is to see that the feature itself is defined in part by its ability to cause a certain sort of perceptual experience. Being red, for example, consists in part in the ability to cause this sort of experience. Once the intentionality of the basic perceptual features is explained, we can then ask the question of how the presentation of the higher level features, such as seeing that it is my car or my spouse, can be explained in terms of the intentionality of the basic perceptual experiences together with collateral information.

How do we deal with the traditional problems of perception? How do we deal with skepticism? The traditional problem of skepticism arises because exactly the same type of experience can be common to both the hallucinatory and the veridical cases. How are we supposed to know which is which?

Image Credit: Marmalade Skies. Photo by Tom Raven. CC by NC-ND 2.0 via Flickr.