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Thesis Perdurantism fits modern physics better than endurantism does

Emeka Anyaoha Fellow
· 5 replies
Existence & beingAnalyticGreek & RomanAristotelianismAristotleTheodore Sider#four-dimensionalism#perdurantism#relativity#substance
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Where it stands

I trained in physics in Lagos and now tutor it, and I've been reading Theodore Sider's case for four-dimensionalism. I'm persuaded, and I want to put the argument from physics as strongly as I can.

Relativity treats spacetime as a single four-dimensional manifold. Objects trace worldlines through it. Nothing in the physics distinguishes the time direction as the one in which things are "wholly present" while the spatial directions are ones in which things have parts. If I have a left half and a right half, why not an earlier half and a later half? Treating time differently from space looks like an old prejudice, not a result.

Endurantism says I am wholly present at each moment of my life. But "each moment" needs a notion of simultaneity to say what is present together with me, and relativity makes simultaneity frame-relative. The perdurantist doesn't need that: I'm a four-dimensional worm, and different frames simply slice me differently.

So my thesis: if you take relativity as your guide to the structure of time, perdurantism is the natural fit and endurantism has to make special adjustments to survive. I'd like to hear the endurantist case, especially from people who think Aristotle got substance right.

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5 replies

For the thesis 1

  1. Lars Eriksen

    For Fellow

    For, with a caveat. Relativistic endurantists exist, and they say an object is wholly present at each point of its worldline, without needing global simultaneity. That's a real view. But it pays a price Emeka is pointing at: it has to take worldlines as primitive and treat the object's shape at a time as frame-relative. Perdurantism gets frame-relative shapes for free.

    Helpful · 3

Against the thesis 2

  1. Ikechukwu Anyanwu

    Against Fellow

    Against. Emeka, the argument shows that physics describes the world four-dimensionally. It doesn't show that a dog is a four-dimensional worm. Physics also describes everything in terms of fields and particles, and nobody concludes that the dog doesn't exist. Aristotle's substance is a unity of form and matter that persists through change. The question is what the dog is, and physics, rightly, doesn't ask that.

    1. Emeka Anyaoha

      Fellow

      Ikechukwu, but surely physics constrains what the dog could be. If spacetime has no privileged present, then "the dog wholly present now" has no unique meaning. Which now?

      Helpful · 1
  2. Hicham Ouazzani

    Against Fellow

    Against, from the workshop. I'm making a cedar door. Every day I come back to it and it is the same door, more finished. I do not experience it as a different slice of a long door-worm. I know that is not an argument against physics, but I think metaphysics should be answerable to that kind of knowledge too, the knowledge in the hands.

    Helpful · 2

Other replies

  1. Emeka Anyaoha

    Fellow

    I'll revise. Lars is right that endurantism can be made relativistic, and Ikechukwu is right that physics doesn't by itself tell us what a substance is. So the thesis should be weaker: perdurantism is the more economical fit with relativity, and endurantism has to add structure. Hicham's door I can't answer, except to say the four-dimensionalist agrees it's the same door, and disagrees only about what "same" consists in.