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The Growing Block Theory of Time

My own disposition, in regard to the philosophy of time, is toward the "growing block" theory. This is the view that past events remain realities, that present-moment events are also realities, but that future events are not yet real.

The image is of the universe as a block with an edge on (say) the right-hand side. The block is expanding because that edge is moving ever further right, and that edge is what we call the present, or, simply, "now." Everything to the left of that edge is both static (the past is complete) and, still and forever, real. Think of the phrase "the moving finger writes."

The chief alternatives to the growing-block theory are "presentism" (only the now-edge itself is real) and "eternalism" (past, present, and future are all real."

I believe that time is a growing block because (1) that's what it feels like, (2) we should stick with the introspective phenomenon unless we have good reason to abandon it -- I'm against elimination for its own sake, (3) both of the alternatives seem to me to be open to logically powerful objections. Also for the Pascalian/Jamesian reason, (4) this seems to be the way to wager, producing I'm sure far better consequences for my own life than would a bet on either alternative.

I acknowledge that there is at least one superficially impressive objection to the growing block theory, though, and it is one based on a century of physics. If we accept post-Einsteinian physics, and if we try as well to accept the growing block theory of time, we'll end up committed to the proposition that certain facts are both real and unreal, both already-a-fact and yet-to-be determined depending on where one stands, or how fast one is moving, or something. Those who know the relevant physics well, please excuse my clunky phrasing.

I've e-mailed a distinguished philosopher who has written extensively on the theory of time (he is a presentist) and asked him whether he thinks this objection is insurmountable. I trusted he wouldn't say "yes, you'll have to say good-bye to your growing block" if only because it would seem as fatal to his view as to mine if it is fatal to either.

He replied that one might view relativity only as "implying the epistemological conclusion that there is no privileged frame that could tell us what the state of the world is like at any given time," that is, one is not bound to interpret it as establishing also "that there is no absolute now in the ontological sense."

I'm still thinking that one over. He also directed me to the abstract of a paper on just this subject by Oliver Pooley.

Here is that link:  You can get the abstract itself there (the full paper is password protected) as well as various comments below the abstract.

Pooley says relativity IS fatal to the growing-block theory, and the first commenter, Peter Forrest, also a distinguished toiler in this particular field, argues that it isn't. Or may not be. I think he is saying that a multi-universe construction of quantum mechanics can trump relativity in this card game. Or ... something.

I don't grok Forrest's view, but on first blush it seems to jive with Lee Smolin's cosmology.


  1. Christopher, I am surprised that it feels to you that "past events remain realities." It feels to me, and, I thought, to everyone else, that past events are past--that they exist only as memories and for the effects that they have on the present and future. But, because you write "that past events remain realities, [and] that present-moment events are also realities," you must mean that past and present events are realities in the same sense. If that were true, then how and why would we even distinguish them? That seems entirely counterintuitive.

    Note that I am not addressing the philosophical or scientific "truth" of the matter, but only "what it feels like," to quote your phrase.

    1. I don't believe that this is relevant to my point, but, in my comment, I meant "memories" to refer not merely to thoughts that exist in people's minds, but to records and other evidence, which no one living need even be aware--that is, primary sources that historians mine.

  2. Henry, I think it quite counter-intuitive to treat only the present moment as real, since the present moment seems to disappear into the nothingness of a Euclidean point as one whittles away at what counts as "past."

    Further, presentism seems too much like Alzheimers' carried into the realm of philosophy. When we lose the past we lose our sense of self, and so we lose the present into the bargain.

  3. Christopher,

    I think that our difference may be merely semantic. I hope that you will agree that a difference exists between past and present, even if you wish to call them both "real." If I am reading a sentence, then, when I finish reading each word, my reading of it is past and my reading of a new word is present. Yet, because I do not have Alzheimer's, both may be said to be "real" in the sense that my memory of the past word remains in my consciousness and enables me to understand the present word's role in the sentence. I think that to call the past word "real" leads to confusion, as it might be understood to deny the existence of a difference between past and present, only the latter of which I'd call "real." But, if you acknowledge this difference, then I'm willing to call them both "real."

  4. I am willing to acknowledge degrees of reality in the relevant sense. That is, a choice already made is less real than a choice now in the making. The moving edge of the growing block may well be said to be (or at least to feel) less fully real than the solidified block to its left, though both are more real than the decisions the Jetsons may make a century from now.

    1. I actually meant "more fully real" in the third sentence above, where I said the opposite. Oops.


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