There are many different ways in which an ontological theory can be criticised. It can be called metaphysically extravagant, unintuitive, or unsupported and unsuggested by empirical findings, or, more damagingly - incoherent and inconsistent. With regards to presentism, the greatest challenge comes from the empirical support for Special Theory of Relativity - a theory which, at least on the face of it, seems to be ontologically committed to the denial of presentism. I will confess - I do not have a sufficient understanding of the special theory of relativity to see exactly how it renders presentism false. Nor do I need to. For my present concern is the absurdity of presentism, not its truth or falsity. Specifically, my charge here is that the theory of presentism is absurd regardless of the other criticisms it might possess. In light of its absurdity, one would need a stronger defence of presentism than what is required for other positions. If anything, the special theory of relativity doesn’t help its case.
What is presentism, then? It is the thesis that all the things which actually exist in the world are here (in a sense of time) and now, and any talk about the past or the future is much like a fictional talk, which has its referent as something which doesn’t exist. One could visualise it as a wafer- thin hyperplane in motion, with the plane representing the present world at this moment of time, with nothing ahead or behind it. This theory stands in contrast to other theories, which might hold that past exists along with the future (like a growing block), or which extend the ontology to the future as well (like a static cube, i.e. eternalism).
Suppose me and a friend are standing in the forest, in anticipation of a tree falling. My friend asserts that the tree will fall. When the tree is falling, I point out that the tree is falling. After it falls, my friend remarks that the tree fell a few minutes ago. Such conversation is perfectly natural, and is how we talk about things and events in the world. According to presentism, however, my friend and me are talking about two different events: while the event I talked about exists in a real sense when I talk about it, my friend is, at all times, referring to a non-existent entity. We are, it seems, talking about different things. If a third friend had asserted that the tree will not fall, and after it falls said that the tree did not fell, there would be no point of disagreement, since he and me are talking about different things altogether. To have any agreement, what we need is a simple correspondence relation between the event we observe in the present, and the event in hindsight: presentism denies this direct correspondence.
Second, presentism’s now, the present moment, is an ill defined concept. How long is a moment? Does it last for a second, a microsecond, a nanosecond? Surely, taking the limit, the now collapses to a duration of zero: pointing out to nothing. On the other hand, if we were to grant the present any finite amount of time, we might as well grant it an extended past, for the supposedly problematic (according to presentism, i.e.) notions of past, present and future apply equally well to the finite interval of time as it does to the whole quanta. On the other hand, if we were to accord this moment a point in a continua, then the absurdity of the concept of now disappears - just as is the case of real numbers and the number line (between any two real numbers, there are an infinite of real numbers, and the measure of every real number by itself is zero).
One might argue that presentism is the only commonsensical view possible. The argument would go like this: If some events or entities exist which don’t exist in the present, where do they exist, then? Where is this past that we talk about (other than in our present heads)?
However, this argument is akin to a man, stuck to a place, denying the existence of far-out places which he can’t go to. Or denying the existence of stars outside the observable universe, just because we can’t perceive them. By contrast, we can give a much better account of the perception of a past and the future if we are to grant that they exist: they exist and can be perceived both by our present self (by memory in the case of past), and also by our past self. The impossibility of physical travel forwards or backwards in time doesn’t add to the appeal of its non-existence just as the impossibility of interstellar travel doesn’t make the non-existence of distant galaxies any more appealing.
Thus, I believe that is is absurd to suppose that only the present exists, because it stands contrary to the way we naturally communicate and operate in this world, and our intuitive conception of time as a continua. In light of its absurdity, one would need a stronger defence of presentism than what is required for other positions. If anything, the special theory of relativity doesn’t help its case.
12 February 2015