Abstract

Suppose that a physical duplicate of me, right down to the arrangements of subatomic particles, comes into existence at the time at which I finish this sentence. Suppose that it comes into existence by chance, or at least by a causal process entirely unconnected with me. It might be so situated that it, too, is seated in front of a computer, and finishes this paragraph and paper, or a corresponding one, just as I do. (i) Would it have the same thoughts I do? (ii) Would it speak my language? (iii) Would my duplicate have any thoughts or (iv) speak any language at all? To fix the interpretation of these questions, I will take ‘thought’ to cover any mental state which has a representational content, where ‘representational content’ is intended to be neutral with respect to psychological mode. By 'psychological mode' I mean what distinguishes kinds of thoughts, such as belief, visual perceptual experience, desire, etc. Representational content, or thought content, as I will also say, determines the conditions under which a thought is true or false, veridical or non-veridical, or, more broadly, is satisfied or fails to be satisfied, independently of relativization to circumstances, possible worlds, or the like. Beliefs, desires, hopes, intentions, and perceptual experiences will all count as thoughts on this usage. The question whether one person has the same (type of) thought as another is the question whether both have a mental state with the same representational content in the same psychological mode. I will not count epistemic verbs, however, as picking out or expressing a (pure) psychological mode. Thus, although knowing that the time is ripe, seeing that there is a goldfinch in the garden, and remembering that my wife’s birthday is next Tuesday are all thoughts, they do not pick out the thoughts by using a verb that expresses a psychological mode. Therefore knowing, seeing or remembering the same things is not a requirement on having the same thoughts..