I am a total hobbyist, but this question bothers me for a long time.

My line of thought is, if there is a collection of rules for which any given event would result in a set outcome with no deviation possible (this is what all forms of determinism have in common according to wikipedia, if i have understood it, maybe i am wrong here already), why should anything happen at all? Meaning why would there be anything if nothing would be mutable in essence, wouldn´t that make existence itself obsolete?

Edit: As the question of what I mean by "Why should there anything happen at all? Why would there be anything if nothing would be mutable in essence, wouldn´t that make existence itself obsolete?" came up often, I´ll try to explain that part a little more in depth.

Keep in mind the first two answer where given before the edit.

Assume the universe is deterministic in the sense that:

  1. for every event x there is an outcome y, such that when x happens the outcome y has to happen
  2. and the event x is the only way the outcome y can happen.

Then x is sufficient and necessary for y, hence y is sufficient and necessary x. Then x and y are essentially the same event, the only way to destinguish x and y would be the order in which x and y took place. This should also hold for every universe which is deterministic, so especially for the universe in which only x and y happen. But in the universe where only x and y are happening we couldn´t possibly uphold that order of events, since x and y are equivalent and we wouldn´t know which one happened first. So if we drop 1. there wouldn´t be anything happening at all and if we drop 2. we are not deterministic anymore. Hope that makes it a little clearer. Feel free to point out any flaw in that argument.

I´m sure this is flawed, but please can someone explain why? Sorry for my bad english.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Philip Klöcking
    Jan 6, 2023 at 20:55
  • I realize this is basically the Münchhausen Trilemma Dcleve pointed me to
    – MathNewbie
    Jan 7, 2023 at 10:32

5 Answers 5


Your sleep deprived intuition is basically correct. The reason that determinism is such an attractive view, is that basically one arrives at it by universalizing the concept of "causation", and ALL of us are hard wired to believe in causation. The simple logic is:

  • everything is caused
  • One can therefore construct a chain of causation, and extend it equally to the future as well as the past
  • Therefore, the future is as determined as the past is.

BUT, as a practical matter, determinism is applied to an initial state, as we cannot do an infinite regress of causes into our past. Which leaves the justification of the initial state "uncaused", breaking the rationale for determinism.

So yes, there is a logic problem in the simplest derivation of determinism.

One will encounter this same logic problem in ALL justifications, and this problem is called the Munchausen Trilemma. ALL justifications must lead to infinite regress, uncaused/unexplained events, or circularity. And all three are considered logic errors. This is an unresolved problem with our reasoning.

As an aside, "everything is caused" is untrue for quantum physics, which extends up to macro scale through chaos phenomena. Our physical world is not deterministic, and our intuitive belief in universal causation is incorrect.

  • 1
    Depends if you accept a narrower definition of determinism, maybe more local: the trajectory of planets according to the law of gravitation is deterministic in that sense, for example.
    – Frank
    Jan 6, 2023 at 19:42
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    I disagree and I think there is an issue that can't be so easily swept under the rug about some aspects of our physical experience being deterministic at least for all practical intents and purposes (the approximation is very good, and/or is not an approximation of a theory we have (no quantum gravity so far)). I think claims such as "our physical world is not deterministic" need more nuance to be accurate.
    – Frank
    Jan 6, 2023 at 19:51
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    @MathNewbie -- Here is an answer on the Munchausen Trilemma, that explains it in "knowledge" terms. The same argument and problem can be recast into "ultimate cause" terms. Basically, the point is we have to live with inability to achieve fully valid reasoning or worldviews. This does not mean we should not critique them, but we should also realize that none will be able to stand up to sufficiently vigorous critique. philosophy.stackexchange.com/questions/64638/…
    – Dcleve
    Jan 6, 2023 at 20:45
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    @Dcleve There is "determinism" as a philosophical position - which is what we are discussing here, and then there is what physics say. I think most physicists would be cautious about asserting that the "universe is not deterministic" - in part because that question has layers and nuances when it comes to theories in physics. The physics SE has several contributions from actual physicists on that question. They appear to be quite cautious.
    – Frank
    Jan 6, 2023 at 21:04
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    @Frank "the universe is determined" is falsified by physics. "The universe has deterministic features" is confirmed. This is a fairly straightforward distinction which has been accepted in every discussion I have had with open minded participants. Asserting your unsourced opinion that "most physicists" might disagree with it, in comments on multiple discussions, is both untrue per my experience, and is starting to look like trollish behavior.
    – Dcleve
    Jan 6, 2023 at 21:15

Your question has many flaws.

X Causing Y Don't In Any Way Mean Y Is Immutable

How it can be? The sentence itself said that Y happened. How can Y's happening mean its not happening?

There Is Only One Way To Y But There Are Many Ways Starting From X - Tree Structure

You are half right thats why you are confused. If you were fully right or fully wrong things would be crystal cleared to you.

Yes, there is only one path to Y. Yes, that path comes from X. But there is nothing in it that say no other path begins from X.

X may cause Y, Z and W. From it may be Z don't cause anything. May be W cause 5 other things.

Your getting degree in medical not only cause you to live a rich life financially but also cause certain patients' lives to be saved who would have died otherwise. One such patient's life saved may later cause a new shopping plaza arising ten blocks down from your residence.

An Event May Have Multiple Causes

You totally ignored this possibility. Your diagram has not only no tree in it (discussed above) but also don't have any graph in it (multiple things causing one thing).

You see just because your father is rich is not sufficient reason you get admission in university. You have to have certain aptitude yourself. Also, the university has to be there.

X is necessary for Y but why do you conclude that its also sufficient for Y?

World is much, much more complex than your model.

There are flaw is in your model. Its a wrong model. It don't reflect reality. Ofcourse its conclusion don't match with reality. Sky, sand and trees exist, don't they?

Just Because X Cause Y Don't Make Them Essentially The Same Event

Y may cause nothing. Chain of events may have an end at Y. Chain of events don't end at X. Its one way X is different from Y.

X don't need Y to exist. Y cannot exist without X. Another difference.

Change in X would effect Y. Change in Y wouldn't effect X. If your mother has certain diseases before she conceive you then you are likely to have those diseases too. If you have those diseases your mother is not likely to get those diseases. Third difference.

Anything other than Y thats caused by Y wouldn't exist if X don't exist, and may be affected by changes in X. Anything other than Y thats caused by X would have none of these. Fourth difference.

Following is for clarity.

Infinite Regression Cannot Happen Therefore There Is A First Cause

We see things causing other things. We see a chain of events.

The chain has to begin somewhere, because you cannot get out of an infinite well.

You are out of the well already (you exist) therefore the well is not infinite. Since the well is not infinite it has a beginning. That beginning is the First Cause.

  • Of course the modell is flawed. It is a universe with only two events taking place, but determinsn should hold in a two event universe if it was universally applicable. Nothing happens when we drop Premise 1. that is the point. X and Y are not the same in that universe, but we can identify X with Y and vice versa.
    – MathNewbie
    Jan 9, 2023 at 15:07

Me two cents ... for what they're worth ...

A is a sufficient cause of B means A is always followed by B.

A is a necessary cause of B means without A, B can't happen.

A is a necessary and suffiicent cause for B is a both of the above together.

The relationship is not symmetric i.e. A being a sufficient and necessary cause for B doesn't imply B is a sufficient and necessary cause for A.

Here's an example that shows why ...

The Fire Triad consists of heat and fuel and oxygen.

Suppose there's heat and there's fuel. In this setup oxygen is the necessary and sufficient cause for fire. But is fire a sufficient and necessary cause for oxygen? Oxygen can be produced without fire (photsynthesis) i.e. fire is not necessary for oxygen and fire doesn't produce oxygen (a log fire consumes oxygen) i.e. fire is not sufficient for oxygen.

You've, in me humble opinion, gotten mixed up with identity (A = B), logical equivalence (proposition A implies and is implied by proposition B means A and B are logically equivalence) and sufficient and necessary causes

  • That is what I mean by essentially the same. Not that x and y are the same event, but they are sperated by the order in which the events take place and we simply can´t decide where it started. Btw. equivalence is indeed a symmetric relation, since for A and B to be equivalent they need to have the same truth value. In order for the fire to burn there needs to be oxygen, but oxygen itseld won´t cause a fire.
    – MathNewbie
    Jan 9, 2023 at 15:24
  • But you are right that the conclusion that x and y are equivalent falls from the sky. Consider it a first draft. Thanks for pointing that out to me. (Keep in mind if I didn´t understand you, I am not a native english speaker, so there is always room for me to misinterpret things or that I make mistakes in my expressions)
    – MathNewbie
    Jan 9, 2023 at 16:01

If you’re saying static universes are deterministic and deterministic universe are static, I think some interpretations of GWR quantum mechanics can possibly defeat the former and objective time passing with Bohmian mechanics defeats the latter.

To defeat static universe are deterministic, consider static block universes with GWR. I’m not sure of a specific article on this, but GWR is a relatively tiny addition to classical theories, (which are often interpreted statically at the block/total level), and changes the ontology from deterministic to objectively random.

To defeat deterministic universe are static, appeal to a deterministic ontology like Bohmian mechanics and believe time passing is objective. Tim Maudlin is an example here.

  • Thanks. This points me in the right direction. I´m currently still an undergrad in math, since I had to start over because of financial troubles. I`m hoping that I´ll finish measure theory this semester and funtional analysis would be next on the list. Not talented though.
    – MathNewbie
    Jan 6, 2023 at 21:08
  • @MathNewbie Hey I'm returning to math undergrad for similar reasons, that's great to hear! Keep it up! I haven't studied measure theory yet but I know it has a ton of applications in physics. My answer is targeted at your "why should anything happen at all" [with and without determinism]. I see determinism as having no necessary bearing on that question, assuming my two reasons are credible. We can have happenings (objective time passing) with and without determinism, and no happenings (no objective time passing) with and without determinism. Time passing is an ancient, unsolved problem...
    – J Kusin
    Jan 6, 2023 at 22:40
  • ...unless you're someone like Maudlin who just takes it at face value that time passes at the deepest level (who also believes in determinism). (Here's one way measure theory is important to modern physics en.wikipedia.org/wiki/Measure_problem_(cosmology))
    – J Kusin
    Jan 6, 2023 at 22:42
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    Functional analysis probably more useful than measure theory per se, although Lebesgue comes in handy for Fourier series, which is part of functional analysis. For QM, Hilbert spaces are also required.
    – Frank
    Jan 6, 2023 at 22:49

There is no flaw in your argument. The flaw is in the premise. Problems arise only if you assume a deterministic universe.

Therefore the only possible conclusion is:

A deterministic universe is a logical impossibility.

Such a universe could not evolve naturally like a normal one and it could not be created by a divine intelligence either.

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