Possible Positions on the Passage of Time


The present exists; the past and the future do not.


The past, present and future all exist.

Growing Block

The past and present exist; the future is coming into existence.

Shrinking Block

The future and the present exist; the past is destroyed as we go.

Growing and Shrinking Block

The future is coming into existence; the past is being destroyed.


The past and future exist; the present does not.


The past, present, and future do not exist.

Random Block

A surprise combination of existence, growth and destruction.

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10 thoughts on “Possible Positions on the Passage of Time

  1. Anonymous

    Isn’t presentism a limiting case of the growing and shrinking block model? (in which the block that exists is reduced to a surface really). Well, this is so, if presentism is okay with saying that future will come into existence.

  2. Bryan

    It’s been suggested (thanks JDN) that we add some possibilities, by taking each of the cases above, and restricting attention to the causal past/future of an observer (or set of observers). This kind of thing was first suggested by Stein (1991).

    So instead of a growing block, we would have a growing cone, etc.

  3. Brad

    I endorse random block, but only when it takes the depicted form, namely, containing a series of love-heart-shaped cross sections.

  4. Bryan

    The Menger sponge spacetime is a cool idea. It’s a compact spacetime! However, it’s ridiculously discontinuous. This is weird, but I think the idea is worth taking seriously. It certainly seems unlikely that there could ever be an experiment establishing the continuity (let alone the analyticity!) of spacetime.

  5. Anonymous

    Comprehensive list, but after Shrinking Block, you sort of lost me LOL.