Memory seems to be a way of spanning temporal perspectives, a description of the world formulated at one time used when Tribing it at another. So, for example, if I am asked to recall the events of the evening of 17 March 1990, I summon up the Description I formulated then and, with appropriate changes in tense, use it to say how things were then. This procedure assumes that there is a single temporal reality onto which all one's various temporal perspectives face, so that the judgements I make at one time can be the basis of knowledge at a later time. This characteristic of memory brings our ordinary reliance on it into conflict with any view which opposes realism about the past. My aim in this chapter is to explain more fully the conflict between memory and antirealism, to show that a kind of realism is engraved in our memories. I begin with some remarks on the rationale for antirealism about the past and then go on to discuss the conflict with our ordinary reliance on memory.
The motive for antirealism about the past has traditionally been a desire to understand hypotheses about particular past happenings in a way that does not make it forever impossible
to find out whether they are true. It received extended discussion by the American pragmatists. There is, for example, a good statement of the point in C. I. Lewis 1956: The assumption that the past is intrinsically verifiable means that at any date after the happening of an event, there is always something, which at least is conceivably possible of experience, by means of which it can be known. Let us call these items its "effects.” The totality of such effects quite obviously constitute all of the object that is knowable. To separate the effects from the object is, thus, to transform it into some incognizable ding an sich. (150–153) Here Lewis was drawing on a tradition of resistance to realism about the past begun by William James and Charles S. Peirce.2 This tradition was robustly maintained by A. J. Ayer: For my own part, I do not find anything excessively paradoxical in the view that propositions about the past are rules for the prediction of those "historical” experiences which are commonly said to verify them, and I do not see how else our knowledge of the past is to be analyzed. And I suspect, moreover, that those who object to our pragmatic treatment of history are really basing their objections on a tacit, or explicit, assumption that the past is somehow “objectively there" to be corresponded to—that it is "real" in the metaphysical sense of the term. ... It is clear that such an assumption is not a genuine hypothesis.
This passage makes explicit the characteristic thesis of antirealism about the past: that understanding statements about particular past events is a matter of being able to verify or falsify them. So understood, a past-tense statement is true if there is evidence presently available for it. This can be qualified a little, since someone who is an antirealist about the past should surely allow that further evidence might turn up in the future. And if he has some sophistication about the notion of evidence being used, he ought to insist that what matters is evidence that we can now recognize as such, since what moves him is reflection on how we presently understand our words. So we can put the antirealist thesis like this: a statement in the
past tense is true just if there is available, now or in the future, evidence for the statement that we can presently recognize as such."
In this chapter my interest is in the way in which our ordinary reliance on memory already stands opposed to any such view. I want to ask just how much of a commitment to realism about the past there is in the way we use memory. So I will set aside some natural objections to antirealism about the past, though I am sympathetic to simple outrage. For example, it might be held to be a consequence of the Second Law of Thermodynamics that there is less information about the past available at one time than was available at an earlier time. On the face of it, the antirealist's thesis means that there cannot be more to the past than there is present or future evidence for, but this seems to run counter to the Second Law. Or again, it might be held that the antirealist has to give a primacy to tensed locutions that they cannot bear; in particular, that Special Relativity is inconsistent with any weight being put on the notion of the present, or now. This response holds that anti realism about the past depends on some privileged status being given to the evidence available now or in the future. But, the response continues, what is happening now, what happened earlier, and what will happen later depend on our choice of a frame of reference, and it is not credible that an arbitrary frame of reference could have such significance. As I said, I will not be pursuing these objections here. I want rather to look at the way in which we ordinarily rely on memory and to ask whether this way involves any commitment to realism. For there is something very distinctive about the way in which the antirealist opposes realism about the past. He holds that temporal real
must always be described from some temporal perspective. consequently, he holds that the perspective from which reality must be apprehended shifts over time.
In contrast, consider, for example, an opponent of mathematical realism, who supposes that what makes mathematical truths true are deep contingencies about human nature, about what we can or cannot imagine or conceive. Someone who takes this line would not say that each of us does in fact occupy different mathematical perspectives at different times. On the contrary, the point of insisting on the depth of the contingencies of human nature in which mathematical truth is rooted is to insist that we cannot simply shake off the mathematical perspective we occupy. Someone opposed to realism about the past, though, has to acknowledge that a single person will, at different times, occupy quite different temporal perspectives. For the antirealist, this is just a way of saying that persons endure. And memory seems to be the way in which persons span different perspectives.