I am a person who believes that conditional proposition. I am not sure if the theory of everything that describes the world is a deterministic one or not, so it is an open question. But are there any philosophers who believe this, and if so, who was the first in recorded literature?

  • It would help if you could support the conditional with an argument. Prima facie, it seems false as determinism is a claim about the actual world only. More particularly, determinism says (very roughly) that the initial state of the actual world / universe plus the actual laws of physics determine every subsequent state of the actual world / universe. This claim is consistent (a) with the existence of other deterministic worlds in which the initial state / the laws are different; and also consistent with (b) the existence of possible worlds that are not deterministic.
    – MarkOxford
    Aug 1, 2017 at 20:37
  • @MarkOxford Well, what I am really saying is that I believe that the only possible world is the actual world. So a statement like "Possibly, unicorns could have evolved" would be a false statement in my view. I just want to know the writings of any philosophers who have argued that viewpoint.
    – user107952
    Aug 1, 2017 at 21:58
  • 1
    Actualism claims that the actual world is the only possible world. Yet even Actualists accept that there are true modal statements (like “Possibly, unicorns could have evolved”) They just don’t interpret them with p.w. semantics. Also, you don’t have to be a Determinist to be an Actualist (or vice versa). The Determinist, too, might accept “Possibly, unicorns could have evolved”: had the initial conditions been different, maybe unicorns would have evolved! (Determinists and Actualists agree the initial conditions could have been different.)
    – MarkOxford
    Aug 2, 2017 at 8:22

2 Answers 2


It depends on the kind of possibilities you're talking about. If you're talking about logical possibilities this is clearly not true. There are conceivable states of affairs that did not occur.

I guess you're talking about possibilities that are not merely "in the head". If you're talking about nomological possibilities (what is possible given laws of nature) this is still not true if you assume "the initial state of the universe could have been different"is true. There are counterfactual possibilities corresponding to different possible universes with different initial conditions.

Now you could assume necessity of the past. Then your statement is true, by definition: if determinism is true, laws of nature determine the future state of the universe and so there's only one possible way the world could evolve.

Finally you could talk about metaphysical possibilities. Many authors since Kripke believe that they are distinct from nomological and logical necessities, in particular because laws of nature "could have been different"metaphysically speaking. In that case, your statement is false because there are metaphysical possibilities corresponding to alternative laws of nature even if the world follows strict laws of nature. But others think that metaphysical possibilities are the same as nomological possibilities (in particular, dispositional essentialists) and others that they are closer to logical or conceptual possibilities.

As to how long people have been thinking that, well, since there are different understanding of possibilities it's hard to say, but questions about necessity and determinism go back to the Greeks.


I'd say it's a common argument of many religious determinists that if there were an ultimate creative being, then every choice of that being would be the only possible one - of course, this is a very specific type of determinist.

From the scientific perspective - I guess the most cited example I've heard is "Laplace's Demon", named for the great French mathematician Laplace - he argued that if a demon (it would probably be easier for us to think of it as a computer) knew the position and velocity of all existing particles in the universe, it could then use the data together with the findings of Classical Mechanics to decide exactly what the future must be. I think that this is largely the argument you present, although perhaps not stated in the same terms.

From my layperson's understanding of modern physics, we currently don't have a known theory of everything, and some of our most critical theories are non-deterministic. However, there is one common possible deterministic physical model I happen to think is fascinating, and I think should be fascinating to anyone interested in determinism: Superdeterminism. Here is Wikipedia on the subject:


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