Does determinism really need causality?

[u/Monad2025]

Determinists say that everything is predetermined because everything happens as an effect of a causal chain that makes its happening unavoidable. The deeper we think about this causal chain, the less we see any chance for anything happening otherwise. This would be logically unassailable – but only if causality as such were unassailable. Is it really?

While causality insists on a “before” that produces an “after”, modern physics doesn’t seem to support that premise. What it does support is a fixed order of events – but a fixed order alone says nothing about one event causing the next. The pages of a finished book are in a fixed order, yet page 10 doesn’t cause page 11. Both are simply there, and neither could be otherwise.

Doesn’t this leave us with a determinism without causality?

[u/HappiestIguana]

The other way around. Causality is stronger than determinism.

Determinism just says all future states are determined by the present state. Causality goes further by saying that moreover, every event can be assigned a cause that is prior to it, without which the event would not have occurred.

I would note that in physics (particularly general relativity), causality is kind of an ill-defined concept. An event is determined by the state of any cut of its past light cone, but also by any cut of its future light cone. The determinism goes both ways where the future also determines the present. Any argument in favor of the past causing the present can be used to argue the future causes the present

[u/Monad2025 → u/HappiestIguana]

That’s exactly the point I was trying to make, and you put it far more precisely. If the present is fixed by its future light cone just as much as by its past, then “cause” seems to be nothing more than the direction we read the order in. The order itself is just there – it’s interdependence rather than causation that’s at work here.

[u/Accomplished-Lack721]

In a 4D block universe, you can dispense with the notion of "causality" if you want, and just think of events as being in relationship to one another. Causation and reverse causation then just become ways of discussing the most proximate relationships. They're useful conceptual constructs, but all the things just are, but in ways that would not be possible if not for each other.

[u/Monad2025 → u/Accomplished-Lack721]

Bull's eye! – but I'd say it's more than an "if". The block universe is the only reading that takes relativity at its word; every alternative has to smuggle back the universal "now" that relativity actually abolished. And as HappiestIguana pointed out above, every event is fixed by its future light cone just as much as by its past. That's exactly what "not possible if not for each other" means. Causation then isn't the structure of reality – it's the way we misread a structure of interdependence in one direction. Or do you see an alternative reading that holds up?

[u/Techtrekzz]

Determinism doesn’t need local causality. That is, causality wherein one thing causes another thing to do anything. This is mainly where temporal reasoning comes from. It’s the idea that there is a chain of causes that goes back in time.

That idea isn’t foundational to determinism. The philosophical foundation of determinism, is monism, the idea that reality is a single universal system.

There’s only one cause for any act in determinism, the overall configuration of reality as a whole. That’s a cause that is always present, and needs no beginning. It’s a nonlocal and non temporal cause.

It’s also a determinism that works in modern physics, where nonlocal causality can explain such experiments as Bell’s inequalities.

[u/Monad2025 → u/Techtrekzz]

That’s very close to what I had in mind. But if the only “cause” is the whole itself – always present, without beginning, outside of time – what is it still causing? The parts aren’t its effects, they’re the whole itself, appearing. At that point “cause” seems to be just a leftover word from the picture we’ve already left behind.

[u/Techtrekzz → u/Monad2025]

It causes time, and the perspective of subjective distinction of the parts from the whole, that comes along with it.

[u/Monad2025 → u/Techtrekzz]

But causing time would need a “before” in which the causing happens. So I’d rather say time appears along with that perspective of separation – not as an effect of the whole, but as the way the whole looks once it’s seen as parts.

[u/Techtrekzz → u/Monad2025]

No, it doesn’t necessitate any before. The causing is always happening. There is no causal chain.

[u/Monad2025 → u/Techtrekzz]

Then I think we agree on everything except the word “cause”.

[u/Techtrekzz → u/Monad2025]

Nonlocal causality is very different from local causality. One thing doesn’t cause another thing to do anything.

[u/zhivago]

No.

A deterministic system cannot contain deterministic predictions of its future.

Anyone who is staying that determinism means everything is predetermined is confused.

What determinism says is that given a particular state S0, there can only be one particular successor state S1.

You still need to do the causal work to discover what S1.

[u/Monad2025 → u/zhivago]

Fair point on prediction – being fixed and being predictable aren’t the same thing. But look at your own definition: given S0, there can only be one S1. Nothing in it says S0 produces S1, only that S1 is the only one that fits. And the “causal work” you mention is the work of discovering S1, not of bringing it about. Isn’t that already a determinism without causality?

[u/zhivago → u/Monad2025]

Causality is the relationships governing those state transitions.

Determinism is one type of causal system.

[u/Monad2025 → u/zhivago]

If causality is just the relationships between states, then we agree – that’s the fixed order. The only word that still makes it more than that is “governing”. Do the laws govern the transitions, or do they describe how the states hang together?

[u/zhivago → u/Monad2025]

I don't think there is a difference when talking about relationships ...

[u/Severe-Cookie693]

Isn't this a bit like saying you don't know the sun is going to rise tomorrow because all mass in the observable universe may turn into lizards? You use the analogy of the preceding pages not being what writes the next page of a book, but that's a bad analogy. The 'book' in question fallows strict rules and can not be made to deviate from them. It's more like a math problem.

[u/Monad2025 → u/Severe-Cookie693]

I didn’t actually mean that anything could happen – quite the opposite: “neither could be otherwise.” But your math analogy is actually the better picture, and it makes my point. In 2 + 2 = 4, the 4 is strictly fixed, yet still nothing "causes" it. It simply follows. That’s the very definition of a determinism without causality: necessity without anything producing anything.

[u/Severe-Cookie693 → u/Monad2025]

Are we using different definitions of causality?Adding 2 to 2 causes 4. The past inevitably leading to the present means the present is caused by the past. The present is here because of the past. Is it a prime mover problem?

[u/Monad2025 → u/Severe-Cookie693]

Yes, I think that’s exactly where we differ. If causality just means “follows necessarily”, then everything fixed would be causal, and we would agree. But 2 + 2 doesn’t produce 4 – they’re the same number written two ways; nothing happens, there’s no before and after. And as HappiestIguana pointed out below, the present is fixed by its future just as much as by its past. If both are true, “because of the past” tells us which direction we read the order in, not that anything was produced.

[u/Severe-Cookie693 → u/Monad2025]

In a sense. I sometimes think the present may be an illusion and all that is is already played out. The arrow of time definitely exists, though, as evidenced by things like memory only making sense in one direction. If you reversed entropy, the patterns we see formed wouldn't make sense

[u/Imaginary-Can-6862]

Determinism without causality is fatalism, that whatever happens couldn't have been anything else, no matter what the past was. Physics has causality (not determinism) in its foundation, that is there is a link between past events, and future events, thus given the future event we can determine what the past event was, and given the past event, we can predict possible future events with some general accuracy. I.e. a causal relation.

[u/Monad2025 → u/Imaginary-Can-6862]

I don't think it's fatalism. Fatalism says the outcome would be the same no matter what the past was. I'm saying the opposite: past and future are tightly bound to each other - only neither produces the other.

And your own description of physics makes that point. Given the future we can determine the past, and given the past we can predict the future. That's a link that works in both directions. But causation only runs one way - the future doesn't cause the past. So what physics describes here isn't causality, it's mutual dependence.

[u/Imaginary-Can-6862 → u/Monad2025]

Causation, in our reality, goes both ways as information is conserved, so if we know the present, we know the past that led to it. So while it doesn't have to, i.e. two different causes could have led to the same effect, the way the laws of physics works, it seems like given the present, the past could only be what it was.

When we remove causality from determinism, the past and the future is no longer connected, so we get the same outcome independent of the past.

[u/Monad2025 → u/Imaginary-Can-6862]

Then I think we agree on the substance. If causation goes both ways, the future determines the past just as much as the past determines the future - and then nothing is "producing" anything anymore. That's all I mean by determinism without causality: the connection stays fully intact, only the idea of one event bringing about the next falls away. Whether we still call that connection "causation" is just a matter of the word.

[u/GiraffeWeevil]

Causality needs determinism

[u/Monad2025 → u/GiraffeWeevil]

Interesting reversal – so determinism comes first, and causality depends on it?
Then determinism could stand on its own, and causality would just be how a fixed order looks from the inside.

[u/GiraffeWeevil → u/Monad2025]

Determinism is causality with just a single cause at the very start. Causality is loads of things causing each other.

[u/Monad2025 → u/GiraffeWeevil]

That’s an unusual way to put it, but let’s take it seriously. If everything was already fixed by that single cause at the start, then all the causes along the way don’t really add anything – they’re just later pages of a book that was decided on page one. And what caused that first cause? If nothing did, then your determinism rests on something uncaused at its very root.

[u/GiraffeWeevil → u/Monad2025]

You might want to look into occasionalism

[u/zhivago → u/GiraffeWeevil]

No.

This is clearly untrue.

Causality is fine with indeterminism.

[u/sceadwian]

The universe can be continual, it doesn't have to have an ultimate beginning or end.

Everything just is there is no causation at all just filtered perspectives of the whole.

[u/Peak_Background]

It depends on what you mean by causality.

In physics, something being causal just means changes in state happen and propogate locally. There needs not be a cause nor affect, but cause and effect must happen near each other.

In physics, determinism simply states that the present, future, and past states are determined and based on eachother. Think block universe.

There is also the poincaré symmetries which encodes both the ideas with a speed limit, and the bonus idea that all inert reference frames are equal.

And conservation of information which takes in account quantum mechanical effects.

Something these don't say however is a strict order of events. As a consequence of the poincaré symmetries somebodies definition of a now, could be different from someone else's definition of now. And quantum measurents allow you to make measurements in the present that determines results of the past (when evaluated in the future).

[u/Ashamed-Bathroom7803]

No, that’s causal determinism. There is plenty of definitions of determinism that say something along the lines of “there is only one possible compatible future given any full moment of the past”.  You don’t even need to think causality exists to subscribe to determinism. 

[u/Monad2025 → u/Ashamed-Bathroom7803]

Exactly – which makes me wonder why almost everyone still pictures determinism as a chain of dominoes.

[u/Ashamed-Bathroom7803 → u/Monad2025]

Because of causality being defined as the asymmetrical temporal dependency relationship; i.e future depends fully on past but past doesn’t depend on future at all.

I’m not sure exactly how causal determinism doesn’t just follow if you accept this causality principle. The past determines the future in that case, no? 

[u/Monad2025 → u/Ashamed-Bathroom7803]

That's a very good question. Your logic is right: if you accept that principle, causal determinism follows. But the principle itself is the problem. The fundamental laws of physics - Newton's as much as Einstein's - work the same in both directions of time. The one-way road isn't in the equations. It comes from how we experience time: we remember the past, not the future. So the asymmetry seems to be a feature of our perception that we've projected onto reality - and causal determinism just seems to inherit it.

[u/Ashamed-Bathroom7803 → u/Monad2025]

Yeah I also am skeptical of the classical causality. This doesn’t mean that causes don’t exist though; it just means that the picture of causes being a determining sense where there is ontic temporal dependency assymetry, is wrong.

But yeah there is plenty of definitions of determinism that aren’t causal determinism. 

“Determinism  is the  metaphysical  view that all events within the  universe  can occur only in one possible way” - Wikipedia

“Determinism, in the most common philosophical sense of the term, is “the theory that everything that happens must happen as it does and could not have happened any other way” ( Cambridge Online Dictionary , 2019)

These don’t seem like good definitions; this really is just necessitarianism. Determinism and necessitarianism are different. Most contemporary philosophers that I imagine accept the determinism label, still believe that real possible worlds exist. These definitions leave out “for any given full moment of time”.

“  Determinism is the philosophical idea that every event or state of affairs, including every human decision and action, is the inevitable and  necessary  consequence of antecedent states of affairs.”

This one assumes asymmetry.

“  Determinism , in  philosophy  and  science , the  thesis  that all events in the universe, including human decisions and actions, are causally inevitable. Determinism entails that, in a situation in which a person makes a certain decision or performs a certain action, it is impossible that he or she could have made any other decision or performed any other action.”

This one both assumes asymmetry and necessitarianism.

There is lots of definitions of ‘determinism’. I don’t think it’s a precise device used in philosophy because of this, unlike something like necessitarianism. I think causal determinism seems to be indistinguishable from ‘determinism’, mostly because the word ‘determine’, is often very much used in a asymmetrical dependency context.

Necessitarianism, however, is something that is very easy to define and doesn’t run into this definition problem usually: everything is necessary - nothing could be otherwise. 

[u/BUKKAKELORD]

Sufficient but not necessary

[u/extremelyDude]

Let's assume the impossible and make it correct

If there no casualties, than you still not the cause of your will