Are qualitative events material? Or should we hold that our conscious, qualitative events are something over and above the events that take place in the physical world? My answer to these questions will be developed over several chapters, but a rough guiding statement of it can be given: if one is willing to make “materialism” a sufficiently empty view, then it cannot be refuted, and qualitative events can be supposed to be material without self-contradiction. If, however, one wants one's philosophical views to be more than purely defensive stances, then dualism should be regarded as the more reasonable view to hold (even though it cannot be demonstrated with certainty).

To begin to clarify these rather compressed pronouncements, it will be helpful to go back to Descartes and consider the fate of an argument that is suggested by some of his formulations.

1. (D1) I am certain that I exist.

2. (D2) I am not certain that anything bodily exists.

3. (D3) I cannot be certain and uncertain of the same thing at the same time.

Therefore,

1. (D4) I am not the same thing as any bodily thing.

Perhaps the most difficult premise in this argument is (D3). Its force may be a little clearer if we consider the following reformulation of the argument.

1. (D1a) I have the property of being a thing of whose existence I am certain.

2. (D2a) No bodily thing has the property of being a thing of whose existence I am certain.

3. (D3a) For every x and y, if x and y are identical, then every property that x has is a property that y has, and conversely.