Online research in philosophy

I want to join Dummett in saying that the reality of the past (and, by analogy, the reality of the future) is an issue of realism versus anti-realism: (Dummett 1969) If you affirm the reality of the past, you are a realist about the past. If you deny the reality of the past, you are an anti-realist about the past. (And likewise, in each case, for the future). It makes sense to think of these issues by analogy with realism about the external world, unobservable objects, mathematical objects, universals, and so on. These are all properly described as ontological issues.

The open future view is the common-sense view that there is an ontological difference between the past, the present, and the future in the sense that the past and the present are real, whereas the future is not yet a part of reality. In this paper we develop a theory in which the open future view is consistently combined with special relativity. Technically, the heart of our contribution is a logical conservativity result showing that, although the open future view is not definable inside the causal geometry of Minkowski space-time, it can be conservatively added to it.

The open future view is the common-sense view that there is an ontological difference between the past, the present, and the future in the sense that the past and the present are real, whereas the future is not yet a part of reality. In this paper we develop a theory in which the open future view is consistently combined with special relativity. Technically, the heart of our contribution is a logical conservativity result showing that, although the open future view is not definable inside the causal geometry of Minkowski space-time, it can be conservatively added to it.

Here are some intuitions we have about the nature of space and time. There is something fundamentally different about the past, present, and future. What is definitive of the past is that the past events are fixed. What is definitive of the future is that future events are not fixed. What is definitive of the present is that it marks the objective ontological border between the past and the future and, by doing so, instantiates a particularly salient phenomenological property of nowness. Call the combination of these intuitions according to which there exists an objective present, a fixed past, and an open future, the intuitive view. I argue that, given the intuitive view, the possibility of backwards causation—and hence, for instance, backwards time travel—is problematic.

Consider also what I shall call the asymmetry of openness: the obscure contrast we draw between the ‘open future’ and the ‘fixed past.’ We tend to regard the future as a multitude of alternative possibilities, a ‘garden of forking paths’ in Borges’ phrase, whereas we regard the past as a unique, settled, immutable actuality. These descriptions scarcely wear their meaning on their sleeves, yet do seem to capture some genuine and important difference between past and future. What can it be? (Lewis, 1979).

There is a tension between the “growing block” account of time (closed past, open future) and the possibility of backwards time travel. If Tim the time traveler can someday travel backwards through time, then he has (in a certain sense) already been. He might discover this fact before (in another sense) he goes. Hence a dilemma: it seems that either Tim’s future is determined in an odd way or cases of (temporary) ontic indeterminate identity are possible. Either Tim cannot avoid heading for the past or he is only indeterminately that guy who appeared in the past with many of Tim’s memories. Determinacy in the past implies a degree of determinism in the future; indeterminism about the future seeps back to the past.

Summary: Contemporary writers often claim that chaos theory explains the thermodynamic arrow of time. This paper argues that such claims are mistaken, on two levels. First, they underestimate the difficulty of extracting asymmetric conclusions from symmetric theories. More important, however, they misunderstand the nature of the puzzle about the temporal asymmetry of thermodynamics, and simply address the wrong issue. Both of these are old mistakes, but mistakes which are poorly recognised, even today. This paper aims to lay bare the mistakes in their classical (pre-chaos theory) manifestations, in order to make it clear that chaos theory cannot possibly do better.

It is often said that, according to common sense, there is a fundamental asymmetry between the past and future; namely, that the past is closed and the future is open. Eternalism in the ontology of time is often seen as conflicting with common sense on this point. Here I argue against the claim that common sense is committed to this fundamental asymmetry between the past and the future, on the grounds that facts about the past often depend on facts about the future.1.