Fred Dretske

(1932 - 2013)

Though one believes that P is true, one can have reasons for thinking it false. Yet, it seems that one cannot know that P is true and (still) have reasons for thinking it false. Why is this so? What feature of knowledge (or of reasons) precludes having reasons or evidence to believe (true) what you know to be false? If the connection between reasons (evidence) and what one believes is expressible as a probability relation, it would seem that the only satisfactory explanation of this fact is that when one knows that P is true, the reasons or evidence one has in support of P are such as to confer upon P the probability of 1. It is shown by an application of Bayes' Theorem that any value smaller than 1 would permit having reasons to believe what one knows to be false. Hence, it would seem that knowledge requires conclusive reasons to believe (if reasons or evidence is required at all)

Causal explanations of behavior must distinguish two kinds of cause. There are triggering causes, the events or conditions that come before the effect and are followed regularly by the effect, and structuring causes, events that cause a triggering cause to produce its effect. Moving the mouse is the triggering cause of cursor movement; hardware and programming conditions are the structuring causes of cursor movement. I use this distinction to show how representational facts can be structuring causes of behavior even though biological events trigger the behavior.

I offer Jimmy a dollar to wiggle his ears. He wiggles them because he wants the dollar and, as a result of my offer, thinks he will earn it by wiggling his ears. So I cause him to believe something that explains, or helps to explain, why he wiggles his ears. If I push a button, and a bell, wired to the button, rings because the button is depressed, I cause the bell to ring. I make it ring. Indeed, I ring it. So why don’t I, by offering him a dollar, make Jimmy wiggle his ears? Why, indeed, don’t I wiggle them? If I ring a bell by pushing a button, why don’t I wiggle Jimmy’s ears by offering him a dollar?That is a question that has always vexed a compatibilist’s vision of human freedom. If an intentional act–say, wiggling one’s ears in order to earn a dollar–is caused by one’s beliefs and desires, then, by the transitivity of the causal relation, it appears to follow that it is caused by whatever causes one to have those beliefs and desires. But the causes of belief and desire are often factors over which one has no control. So intentional behavior is often something one is made to do by factors over which one has no control. This, however, robs intentional behaviorand, presumably, also voluntary action–of its autonomy. Deliberate acts–Jimmy wiggling his ears to earn a dollar–have the same causal structure as does a bell that rings because a button is pushed. The only difference is the switch.

This book presents an attempt to develop a theory of knowledge and a philosophy of mind using ideas derived from the mathematical theory of communication developed by Claude Shannon. Information is seen as an objective commodity defined by the dependency relations between distinct events. Knowledge is then analyzed as information caused belief. Perception is the delivery of information in analog form for conceptual utilization by cognitive mechanisms. The final chapters attempt to develop a theory of meaning by viewing meaning as a certain kind of information-carrying role.