Causing and signifying
… why could nature not … have established some sign which would make us have the sensation of light … it is our mind which represents to us the idea of light each time our eye is affected by the action which signifies it.
Descartes, Le monde, ch. 1
I want to explore the question of the relation between perceiving objects and the role objects play in perception. I shall examine several recent articles and books which deal with this relation. I do so against the background of seventeenth- and eighteenth-century discussions of that relation and of the nature of perception. The causal theory of perception is often associated with some of the writers in those centuries.1 The causal theory of perception says that objects (and their actions) cause us to perceive them. Presumably the claim is more than merely that I perceive the desk when certain physical events (light rays, electrical and chemical events) occur; there is more than concomitance and correlation. The theory says that the physical processes (events) from object to nerves and brain are necessary and are parts of the cause of conscious perception. The nature of the causal process is usually explicated by the physical sciences: physics, chemistry and optics. But my experience of perceiving the desk is not itself one of the physical events in this process. So we need to ask “what is the total set of necessary and sufficient conditions for perception?”
There does not seem to be an account of the causation of sense experience,other than the account of what happens in nerves and brain, but events in nerves and brain are not the experience of seeing a desk, or even of being aware of sense qualities. Physical causation seems to some philosophers incapable of “causing” my seeing, no matter how impor-____________________