Fred Dretske

(1932 - 2013)

Gettier constructed his well-known examples by assuming two things: (1) that the justification needed to know is the kind one can have for a false proposition; and (2) justificational closure— that justification is transmitted through known implication. I think both assumptions are false. Although I have elsewhere disputed (2), I will set that topic aside here. In this chapter I will, instead, challenge (1) by showing that if you accept (2), or any reasonable approximation to (2), you cannot accept (1). The justification needed to know must be conclusive, the kind of justification one cannot have for a false proposition.

An attempt to develop a theory of knowledge and 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 caused belief. Perception is the delivery of information in analog form (experience) for conceptual utilization by cognitive mechanisms. The final chapters attempt to develop a theory of meaning (or belief content) by viewing meaning as a certain kind of information-carrying role.

Epistemology, or the theory of knowledge, is concerned with how we know what we do and what justifies us in believing what we do. In this anthology, Sven Bernecker and Fred Dretske have collected the most important and influential writings, organized into fifteen subject areas that are key to a broad understanding of contemporary theory of knowledge. A readable introduction to each subject area outlines the problems discussed in the essays that follow. A brief synopsis to each reading clarifies the aims of the author so readers can more effectively focus on analysing the essay.

Melnyk complains that my account of the way reasons explain behaviour cannot be extended to cover novel behaviours. I admit that I did not extend it, but deny that it is not extendible. This, indeed, is what Chapter 6 of Dretske (1988) was all about. Noordhof finds faults with my account and claims there is another account (partial supervenience) that does a better job. I acknowledge one of the defects—a defect I was aware of when I wrote the book‐but deny that the partial supervenience of content on intrinsic properties represents a better theory of the explanatory role of content.

A theory of information is developed in which the informational content of a signal (structure, event) can be specified. This content is expressed by a sentence describing the condition at a source on which the properties of a signal depend in some lawful way. Information, as so defined, though perfectly objective, has the kind of semantic property (intentionality) that seems to be needed for an analysis of cognition. Perceptual knowledge is an information-dependent internal state with a content corresponding to the information producing it. This picture of knowledge captures most of what makes knowledge an important cpistcmological notion. It also avoids many of the problems infecting traditional justificational accounts of knowledge (knowledge as [justified, true belief’). Our information pickup systems are characterized in terms of the way they encode incoming information (perception) for further cognitive processing. Our perceptual experience is distinguished from our perceptual beliefs by the different way sensory information is encoded in these internal structures. Our ropositional attitudes – those (unlike knowledge) having a content that can be either true or false (e.g., belief) – are described in terms of the way internal (presumably neural) structures acquire during learning a certain information-carrying role. The content of these structures (whether true or false) is identified with the kind of information they were developed to carry.

If we think of the objects (as opposed to the facts and properties) we see as the objects we are visually conscious of, the texture of conscious visual experience is given by the number of objects we see. By using an epistemic test for the objects we see (viz, the objects one sees are the objects one has direct perceptual knowledge of) it is argued that the texture of conscious experience is very rich indeed — much richer, in fact, than studies of change blindness and inattention would suggest. We know, by direct visual perception, more than we know we know. We are therefore — often enough anyway — aware of more than we realize. A subjective, first-person, test for consciousness is the wrong test.