Key Arguments

• Parfit introduces the Wittgenstein–Quine objection that science‑fiction cases allegedly overreach, by trying to say what is 'logically required' for sameness of person under unprecedented circumstances, as if words had a hidden logical force beyond their actual use.
• He grants that this criticism 'might be justified' only under a specific condition: if, when considering such imagined cases, we had no reactions; that is, if they did not engage our intuitions at all.
• He insists that in fact 'these cases arouse in most of us strong beliefs', so the antecedent of the criticism fails; people do have robust, spontaneous reactions.
• He emphasizes that these are 'beliefs, not about our words, but about ourselves', directly targeting the linguistic/conceptual focus of the Wittgenstein–Quine critique.
• He claims that by reflecting on such cases 'we discover what we believe to be involved in our own continued existence' and 'our beliefs about the nature of personal identity over time', showing that the epistemic payoff concerns metaphysical self‑conception, not semantics.
• He further notes that although these beliefs are revealed most clearly in imaginary cases, 'these beliefs also cover actual cases, and our own lives', underscoring that the method illuminates ordinary, real‑world identity judgments.

Source Quotes

And, while I stand here speechless, I can see and hear myself, in the studio on Mars, starting to speak. What can we learn from this imaginary story? Some believe that we can learn little. This would have been Wittgenstein’s view.1 And Quine writes: The method of science fiction has its uses in philosophy, but. . . I wonder whether the limits of the method are properly heeded. To seek what is ‘logically required’ for sameness of person under unprecedented circumstances is to suggest that words have some logical force beyond what our past needs have invested them with.’2 This criticism might be justified if, when considering such imagined cases, we had no reactions. But these cases arouse in most of us strong beliefs.

I wonder whether the limits of the method are properly heeded. To seek what is ‘logically required’ for sameness of person under unprecedented circumstances is to suggest that words have some logical force beyond what our past needs have invested them with.’2 This criticism might be justified if, when considering such imagined cases, we had no reactions. But these cases arouse in most of us strong beliefs. And these are beliefs, not about our words, but about ourselves.

But these cases arouse in most of us strong beliefs. And these are beliefs, not about our words, but about ourselves. By considering these cases, we discover what we believe to be involved in our own continued existence, or what it is that makes us now and ourselves next year the same people.

And these are beliefs, not about our words, but about ourselves. By considering these cases, we discover what we believe to be involved in our own continued existence, or what it is that makes us now and ourselves next year the same people. We discover our beliefs about the nature of personal identity over time.

By considering these cases, we discover what we believe to be involved in our own continued existence, or what it is that makes us now and ourselves next year the same people. We discover our beliefs about the nature of personal identity over time. Though our beliefs are revealed most clearly when we consider imaginary cases, these beliefs also cover actual cases, and our own lives. In Part Three of this book I shall argue that some of these beliefs are false, then suggest

Key Concepts

• What can we learn from this imaginary story? Some believe that we can learn little. This would have been Wittgenstein’s view.1 And Quine writes: The method of science fiction has its uses in philosophy, but. . . I wonder whether the limits of the method are properly heeded. To seek what is ‘logically required’ for sameness of person under unprecedented circumstances is to suggest that words have some logical force beyond what our past needs have invested them with.’2
• This criticism might be justified if, when considering such imagined cases, we had no reactions. But these cases arouse in most of us strong beliefs.
• And these are beliefs, not about our words, but about ourselves.
• By considering these cases, we discover what we believe to be involved in our own continued existence, or what it is that makes us now and ourselves next year the same people.
• We discover our beliefs about the nature of personal identity over time. Though our beliefs are revealed most clearly when we consider imaginary cases, these beliefs also cover actual cases, and our own lives.

Context

End of section 10 ('WHAT WE BELIEVE OURSELVES TO BE'), immediately after narrating the teletransportation and New Scanner story, Parfit pauses to ask what can be learned from such an imaginary story and defends the philosophical use of these thought experiments against Wittgenstein’s and Quine’s reservations.