1. What is the Problem of Personal Identity?

Locke posed the problem of personal identity in one brief question, “What makes the same person?” This formulation is deceptively simple. My aim is to offer a new interpretation of the problem and to suggest a method for finding a solution.

Investigations of personal identity are usually cast in terms of finding the criterion for personal identity. Yet talk of criteria is ambiguous. In one sense of the term, the criterion of personal identity would be special evidence for personal identity. According to the second usage, the criterion of personal identity would be that state of affairs for which evidence for personal identity is evidence. We will not be concerned with the first construal. On that reading, the problem of personal identity would be an epistemological issue. But the basic question concerning personal identity, “What is one person?” does not appear to be an epistemological question.

This commentary offers two criticisms of Block's account of phenomenal consciousness and a brief sketch of a rival account. The negative points are that monitoring consciousness also involves the possession of certain states and that phenomenal consciousness inevitably involves some sort of monitoring. My positive suggestion is that “phenomenal consciousness” may refer to our ability to monitor the rich but preconceptual states that retain perceptual information for complex processing.

David Marr's theory of vision has been widely cited by philosophers and psychologists. I have three projects in this paper. First, I try to offer a perspicuous characterization of Marr's theory. Next, I consider the implications of Marr's work for some currently popular philosophies of psychology, specifically, the “hegemony of neurophysiology view”, the theories of Jerry Fodor, Daniel Dennett, and Stephen Stich, and the view that perception is permeated by belief. In the last section, I consider what the phenomenon of vision must be like for Marr's project to succeed.

Three recent, influential critiques (Stich 1978; Fodor 1981c; Block 1980) have argued that various tasks on the agenda for computational psychology put conflicting pressures on its theoretical constructs. Unless something is done, the inevitable result will be confusion or outright incoherence. Stich, Fodor, and Block present different versions of this worry and each proposes a different remedy. Stich wants the central notion of belief to be jettisoned if it cannot be shown to be sound. Fodor tries to reduce confusion in computational psychology by dismissing some putative tasks as impossible. Block argues that the widespread faith in functionalism is just not warranted. I argue that all these critiques are misguided because they depend on holding cognitive psychology to taxonomic standards that other sciences routinely rise above.

Most people believe that extraterrestrial beings or porpoises or computers could someday be recognized as persons. Given the significant constitutional differences between these entities and ourselves, the general assumption appears to be that ‘person’ is not a natural kind term. David Wiggins offers an illuminating challenge to this popular dogma in ‘Locke, Butler and the Stream of Consciousness: and Men as a Natural Kind’. Wiggins does not claim that ‘person’ actually is a natural kind term; but he argues hard for the advantages of regarding it as something like a natural kind classification. The problem is that, whatever its merits, there are obvious and fatal objections to the view that person is a natural kind. My aim is to present a modification of the natural kind thesis which avoids these objections and retains the attractions of the basic position.