It seems to me that we ought to be rather indifferent to their existence. Take free will, for example. By the nature of how it's defined, and its incompatibility with science, it can't be proven nor disproven to exist. So why should we care? If it exists, then nothing changes. If it doesn't, then nothing changes. Either way, it will either have always existed or not existed, and it wouldn't change how we live our lives. In fact, I think the only aspect of free will that effects how we live is whether or not you believe in it, since this may change your outlook on the world and therefore effect how you make choices. I think, clearly, it's rather arbitrary which way we believe, and therefore we should just choose not to believe one way or the other, and allow ourselves to live independently of any belief in free will, since not doing so would be unfounded and possibly restrictive.

Same with the idea of a god. Its existence could never be proven nor disproven, and whether or not it exists has no impact on how we live. The only aspect of it that does impact how we live is our belief in it. But this belief is only possibly restrictive, whether it's for or against, so why should one believe either way?

If you know any mathematical logic, I mean this in a similar way to how the continuum hypothesis is independent of ZFC. It seems to me that we should simply allow ourselves to be independent of these metaphysical ideas and not make an arbitrary choice one way or the other in terms of our beliefs in them.

Despite this, I see people all the time, including philosophers, argue for or against certain metaphysical ideas, including free will and a god. Are they simply mistaken, or is there a reason for this? Or, is it that my understanding of what it means for something to be metaphysical is flawed? I'm interested to hear what others think about this.

Edit: To be clear, I'm not asking specifically about the questions of free will or the existence of a god, and am only using those as prominent examples. My question is more so focused on the bigger picture, of whether or not questions of similar nature bear any usefulness at all, as opposed to specifically asking about those examples.

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    The existence or non-existence of free will has implications on justice, welfare, etc. The existence or non-existence of a god depends on the god: Discussing whether people will be tortured for all eternity does seem consequential. Discussing the existence of a pantheistic or deistic god who is nature or who did nothing beyond creation is probably completely pointless.
    – NotThatGuy
    Commented Jun 17 at 4:01
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    This seems a bit too broad and it's probably better to ask separately about the use of arguing about free will and the use of arguing about the existence of a god. There are already related questions about each (albeit they aren't exact duplicates): What are the implications of accepting that we don't have free will? and Why should I seek to determine the ultimate nature of reality (i.e. whether God exists or not)?
    – NotThatGuy
    Commented Jun 17 at 4:07
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    @NotThatGuy I think if our justice or welfare system depends on the existence or non-existence of free will, then it's inherently flawed. It should depend instead on something more tangible, like science on what's most effective in producing "good" or "healthy" citizens. The consequences you mention are only as substantial as the premise of free will or the lack thereof, which has no substance whatsoever. Commented Jun 17 at 4:29
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    I would say we probably have already built our justice and welfare systems assuming the existence of free will, to varying degrees (and there are many statistics showing flaws there). So it's not so much that I'd say we should build those systems on free will, but rather the non-existence or incoherence of free will undermines the foundation of those systems, and we need to redefine them to be more sensible and empirical.
    – NotThatGuy
    Commented Jun 17 at 5:04
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    The free will example is something of a special case, in that the answer changes what the optimal decisions we should make are, but the strategy of always assuming there is free will and acting accordingly is always optimal, since if there is free will, acting as though there is free will is the best of the two options we had, and if there's not free will, acting as though there is free will is the best of the one option we had. W.r.t. the continuum hypothesis, it might still be nice to know if it's true; it's just that ZFC doesn't give us the tools to prove it.
    – Ray
    Commented Jun 17 at 16:52

7 Answers 7


Here are the main assumption(s) that some ppl break with:

(a) Crucially, the notion of proof here is unclear: we can formalize definitions of free will, add an accepted formal system and suitably formalized theory and prove or disprove existence wrt to that theory. Or perhaps you mean prove informally, as in argue with some epistemic certainty that one or the other holds given some body of premises. But many philosophers do claim to have done this. Yes, their claims contradict each other. But does this straightforwardly mean that we can have no epistemic confidence in either conclusion, ie that we can assert agnosticism? To make this move is to assume a position on the epistemic nature of disagreement, I discuss this briefly here: Does it matter if certain professions have a lower rate of theism, and if so, why does it matter?. See also the SEP on disagreement for a high level overview. Otherwise, one must revert back to an examination of the "first order" metaphysical evidence, and argue for or against a metaphysical position. But this is just what you are questioning the value of. OFC, this is not to say that some sort of metaphysical agnocisticsm is untenable, just that it must be argued for, whether directly or indirectly. The only other way I can read this would be as a global skepticism, which seems somewhat untenable (but for more, see as always https://plato.stanford.edu/entries/skepticism/)

(b) Your general sentiment is then that metaphysical entities have or should have no impact on how we live. (*) But it seems that this sentiment rests directly on point (a, iii) which is at least debateable, as shown above. Now, for a positive account: People generally want to believe in true things and wish to live their lives according to those truths. This is one of the main values of metaphysical eqnuiry: they are searching for truth. Thus, to value truth is in some way to value metaphysical enquiry. Further, metaphysical positions are commonly assumed in public discourse: people believe in an objective good for rational beings mediated by human rights, justice systems are founded based on free will, abrahamic religions based on the existence of a god. So it is important to explore the discourse, since many people and public instituions value it and attempt to persuade others by it.

(*) This must be fleshed out further. For if god exists, presumably they can alter our universe in ways that would truly affect us, regardless if we believe in them. So perhaps you mean this claim for other things: like free will, causation, objective good.

  • I see what you mean regarding the practical reason to argue these things; since people believe in them and that has real consequences. I suppose I fell into the trap of looking at it from an abstract point of view, despite arguing against exactly that. I actually did write a lot regarding what I meant by "proof" but scrapped it cause I didn't want to get caught up in the details for what was meant to just be an example. It was similar to your epistemic description. Commented Jun 17 at 7:58
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    On wanting to believe and live by true things, I think this is a fallacy in itself. I think the idea of objective truth is kind of ridiculous, as I more or less suggested in my post, and I don't think anything can be known with any certainty. But I think the mistake is to think that that matters. We live our lives regardless and, whether we like it or not, all that we have to go off of is our experience itself. I guess a better way to have asked my question is to ask why that isn't the common consensus and what reason do philosophers have to argue against it? Commented Jun 17 at 8:22
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    It's clear to me now that I didn't have my thoughts very well organized before, and wasn't properly expressing myself., although I thought I was. I appreciate your answer. Commented Jun 17 at 8:24
  • What if the truth is, that there are not the kind of truths that people would like to live their lives by, and we have to find lesser truths to hold dear?
    – Scott Rowe
    Commented Jun 17 at 17:19
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    "metaphysical positions are commonly assumed in public discourse" public as in the people on the planet or public as in the philosophical community? Because I don't think anyone around me care about metaphysics at all. Human rights in the public discourse is overwhelmingly based on reciprocity, aka let's collectively agree to be nice to each other. This is all the more apparent when you read through youtube comments on murder trials and see that there is zero concern for the rights of the accused/convicted.
    – Passer By
    Commented Jun 17 at 17:45

I will generalize your question a bit, hopefully this is still interesting to you too:

If the outcome of a debate cannot possibly have an impact on my (our) lives, then why take part in the debate? Why take any position?

I propose three possible answers. The first two may be seen as side-stepping the question, but still seem relevant to me:

  • Philosophy can be practiced as l'art pour l'art, intellectual puzzling for its own sake; the problems are intriguing, we derive pleasure from reading a good argumentation, even if it's useless
  • Debates are always embedded in a wider context. The direct outcome, the outcome sofar, or the expected outcomes, may not have an impact on the beliefs of the participants or the public, but there may be meta-values in play: The participants could be debating because that's how they make money as academics. The debate could exemplify to the listeners (for instance to children) how to conduct a smart, respectful, non-violent, debate.
  • The boundary between questions that can be decided by empirical research and those that can not is fuzzier than it may appear. The boundary between the useful and useless may be fuzzier than it appears.

The l'art pour l'art practice of philosophy may appear as "useless" or even "frivolous". The endless debates of philosophers may appear to be abstruse and ridiculous to scientists. I believe it's an empirical fact that many scientists do not read philosophy and are not aware of what's happening in academic philosophic - and this doesn't seem to hinder them in any way in their pursuits.

The philosophical project of trying to "ground" science in an ultimate, unassailable, absolute truth - a truth that can be used as basis or scaffold of all knowledge, and that, once established will remain standing forever, the Truth with capital T that Descartes and Spinoza thought to have found - is no longer taken seriously by scientists, I think, at least not as a scientific project. The essence of science is not knowledge (a possible, but always contestable and unsure outcome) but research, inquiry. To conduct research and reach (temporary, mutable, conditional) consensus, we do need some explicit standards and methods, but those need not be ultimate or absolute. The standards and methods may change as we go along (which doesn't mean they are arbitrary or subjective).

Those relativist ideas about science - the ones I just hinted at - are themselves born from philosophical debates, scientific inquiries, historical studies. They hint at a philosphy of science that can itself not be totally scientific and is still somewhat up in the air -- up for debate. Also, there is a fuzzy border around science that leaves room for questions that currently are not scientific, or cannot be decided by science, but may at some point become so - because our theories and methods become more powerful, our language more expressive, or because we observe relations among phenomena that we didn't observe before.

Example: "Are atoms real? Do they really exist or are they just a mental construct, part of a theoretic model to explain certain processes? Parts of the atomic model may be testable but is the core assumption (that atoms themselves exist) verifiable?" Up to the last century, up to Einstein's study of brownian motion, this question could be seen as "metaphysical" or "borderline-metaphysical", with Ernst Mach as one of the last serious holdouts to advocate against the reality of atoms. But Mach lost this debate. As one chemist famously remarked:

We know that atoms and molecules exist because we can see them.

(P.W.Atkins, Physical Chemistry, 1986) (Some crackpot philosophers might try to reopen this debate, but do we want to listen to them? Physicists will just shrug them off.)


A variation on that last debate actually lives on in the debates about observables/unobservables in so-called constructive empiricism. Personally, I side with Ian Hacking's criticism of the anti-realist, constructive empiricist position -- which is the position that there is a relevant epistemic distinction to be made between seeing things with the naked eye and (for instance) seeing things through a microscope. Van Fraassen's reply to that seems sharp, but also subtly misleading. Also, in its broad outline, I believe that constructive empiricism is misguided. -- In mathematics we can see that intuitionist, constructive mathematics is actually relevant as a mathematical project; it's being pursued by mathematicians, not just as a philosophy of math. Is constructive empiricism relevant in a similar way? Is it actually directly being carried by scientists and making a difference?

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    I like the part about the usefulness of discussion and debate.
    – Scott Rowe
    Commented Jun 17 at 17:14

Of course there is a reason. God is the main religious concept, and religion is a social institution of control and power. People defend the concept they were brainwashed with since childhood to keep the system functioning (it doesn't matter how conscious they are about it)

The reasons are purely pragmatical and has nothing to do with philosophy. It's mega useful for any church/ideology to spread its ideas, therefore arguments but not in the sense you look at usefulness. :)

  • "If I had asked people what they wanted, they would have said, 'better brainwashing'." Science just needs to get started in the schools earlier, with more interesting textbooks and things. We could pass laws to make sure it is taught...
    – Scott Rowe
    Commented Jun 19 at 10:40
  • We could put up plaques in public locations with Maxwell's Equations and Newton's Laws and math axioms and so on. How could anyone challenge that legally? They are the laws of reality, no matter which religion one might like.
    – Scott Rowe
    Commented Jun 19 at 10:48
  • @ScottRowe well, it's not just abstract religion, it;'s also politics. If you believe in this, there is higher chance you'll vote for this guy. etc etc
    – Groovy
    Commented Jun 19 at 13:21
  • Who is the Science candidate? They have my vote!
    – Scott Rowe
    Commented Jun 19 at 22:21

You ask:

What is the use in arguing for or against the existence of metaphysical things?

Coming from a position heavily influenced by the linguistic turn, the existence of what might better be called abstractions, have an important purpose. Freewill, God, and other highly non-empirical concepts serve to model the world around us, for better or worse. Consider the impact of freewill on the US judiciary.

On the one hand, if you choose to commit a crime like 1st degree murder, you are likely to spend a long time if not your life in prison. In particularly egregious cases, you might be executed. Should student drunk drivers who kill be treated the same as psychopathic serial killers? So, the same criminal act if done without intention or under coercion will elicit a lesser penalty, and that appeals to our sense of justice. This isn't possible without notions like consciousness, mens rea, and freewill.

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    Dogs with rabies bite, they have no choice about it, yet we still (permanently) stop them from biting anyone else. To me, lack of free will strengthens the case for removing people from society if they do harmful things. To get leniency, you had better show that you could have done differently if you had different information or choices in front of you.
    – Scott Rowe
    Commented Jun 17 at 16:59
  • @ScottRowe Freewill, whether or exists or not, is certainly a good measure of deciding what should be allowed. Scientific instrumentalism would simply grant us that an operational definition of freewill according to the modern psychological sciences, achieves exactly the end, regardless of whether some is scientifically real or not...
    – J D
    Commented Jun 17 at 19:29
  • The OP should consider that scientific realism itself maybe nothing more than a collection of well-tested, but ultimately uncertain hypotheses beholden to the scandal of induction.
    – J D
    Commented Jun 17 at 19:29
  • It's perfectly possible without freewill concept. We can look at some human as a robot, robot performs accident, causes harm, we remove it and isolate it. Regardless if it had freewill or not, just for security reasons. and also, because robots are self-programmed, to program other robots not to do it by showing what happens, and robots have programs of self preservation. Again, no need for freewill.
    – Groovy
    Commented Jun 18 at 9:23

With regard to the continuum hypothesis you mentioned, it is worth noting that there are indeed some mathematicians who view it as a kind of "metaphysical thing" as you put it. Solomon Feferman was one of them.

However, other mathematicians feel otherwise, and there has been a healthy debate with nontrivial mathematical/logical content as to which is the preferable form of a foundational assumption in this context. Currently a leading view among (some) experts seems to prefer the idea that the continuum hypothesis itself should be rejected in favor of the assumption that alef-1 is still strictly smaller than the (real) continuum but alef-2 is equinumerous with the continuum; see for example this post: https://mathoverflow.net/questions/307140/mathematical-evidence-backing-mathbbr-aleph-2

I suspect that the situation is similar with other more philosophical areas involving discussions of what you call "metaphysical things"; namely, that it could lead to fruitful discussions. As you acknowledge in your question, such choices affect the way one could lead one's life, and hence they are not merely "academic".


In general, humans are curious. When we observe phenomena in the world, we want to know what causes them. This curiosity leads to research and development, and the end result has been our tremendous mastery of the world and the success of our species. There are other creatures with some levels of technology (beavers are very effective dam builders, which impacts the flow of rivers) but no species has the breadth of influence over the world that we have.

And it's not always possible to know what knowledge will prove useful. There have been many instances where something that was studied for purely theoretical reasons eventually found application in technology. For instance, 19th century topology led to the understanding of manifolds, which Einstein used in his formulation of general relativity; this became useful to the development of gravity wave detectors like LIGO.

So we study and debate whatever we find interesting. Sometimes we'll come to conclusions that have an impact, other times we won't. Often the process itself will have productive "meta" effects, such as improvements in the debate process itself or the development of the scientific method. A general assumption is that there's little downside to increasing knowledge.


There are two questions which we must ask here which I believe that you might be conflating.

One is what can we prove and the other is what should we believe. No, we cannot currently prove Free Will or determinism or the existence or non-existence of God. We cannot prove whether or not there is a teapot in space. We cannot even prove that nature is uniform (and therefore that science is even possible). So, the question about what we can prove is interesting, but not really the important distinction here. I will, however, make an exception in that if there is a God of the type many believe to exist, then we will certainly at a later point be able to prove his existence. This is not true for the inverse.

The more important question is what you hint at with asking how it would change how we live our lives. I think that this implies impetus, or what should we believe. This is a much different question and one which makes a better distinction.

Regarding Free Will, I personally believe that this is not a very useful belief in that it does not, as you noted, change how we should live our lives. If I cannot act according to my own will, then I am not harmed by trying to act as if I can. As a metaphysical question, I find it ultimately uninteresting except to point out its futility. This does not, however, mean that there is no other use. For instance, it is an important topic inside of some Christian theology because it has to do with the nature of God and the nature of man. Even here, it does not actually change how we should act, but in some sense is a matter of aesthetics, similar to how artists might discuss the beauty of a classic painting. The trap is when people attempt to debate different views of Free Will as if it negates the metaphysical relevance of religion.

The question about the existence of God, on the other hand, is possibly one of the most important questions that a person could ever ask, having the greatest utility possible, but mostly as part of a larger question about what is important to believe at all. In particular, if there is a God, then there might be an objective morality, and if there is an objective morality, then that colors every decision that we make. Furthermore, it provides information about every aspect of our observation of the universe.

If we use this later distinction, we can better know what questions are important and why they are important. I think that most people ask questions which they believe to be important. I don't think anybody, for instance, spends much time debating what color a rose might be on Jupiter if it could grow roses. The problem is that some people, usually through cognitive dissonance, ignorance, or bad faith arguments, attempt to focus on questions which are not actually important, or perhaps to remove them from the context in which they are important. The fact that we might or might not be able to prove a thing to be true is actually the thing which, in many cases, is unimportant.

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