A Case for the Principle of Sufficient Reason

Let us workshop this defense of the Principle of Sufficient Reason (PSR), the key principle behind my case for Chronological Determinism and Necessitarianism (as well as for God).

A Case for the Principle of Sufficient Reason

1. Introductory Remarks

In earlier posts I defended both Necessitarianism, the view that whatever obtains is guaranteed to obtain, and Chronological Determinism, the view that the future is guaranteed by the past. These positions are often seen as highly upsetting. They entail, after all, that nothing is ultimately up to any human. The central way to attack these positions is to attack the principle that appears to be their lifeblood: the Principle of Sufficient Reason (PSR).

In this post I will defend the PSR, employing some of the moves I make in my paper “A Rationalist Defense of Determinism” (and, to a lesser extent, “A Cosmo-Ontological Case for God”). Before I do so, however, I will describe the PSR and then try to steelman, so to say, the case against it.

2. What is the PSR?

You cannot get more commonsensical than the PSR. The PSR is a principle that all of us, with exception mainly to certain specialists in philosophy, implicitly endorse. We all believe, that is to say, that each thing—where by “thing” I mean whatever has ontological oomph (events, states of affairs, processes, possibilities, hallucinations, or whatever)—has an explanation for why it is exactly the way it is (for its existence, for its being true, or so on). If you believe that nothing comes from nothing, as the saying goes, then you believe the PSR is true.

According to the PSR, there is a sufficient cause for why whatever happens happens, in which case it is impossible for something—some reality, some being (whether it be an apple in my hand, an assassination event, a forest fire, a desire for ice cream, a hallucination of a pink elephant, or so on)—to come from nothing (nonreality, nonbeing). The PSR, in effect, entails that there is a complete answer to every why-question. No, this does not mean that humans know the answer to every why-question. Rather, it means that there is an answer—an answer that a powerful enough mind (God’s mind, say) could understand.

Let me put the point in different terms. According to the PSR, there is an adequate reason for why whatever occurs occurs, a non-merely-partial explanation for why whatever happens happens—yes, even if no human could fully detail such a reason or explanation. By “reason” or “explanation,” it is important to understand, I do not mean a purpose, as in when people say: “There must be a higher purpose for the forest fire that killed so many animals.” Rather, I mean that there is a causal story to tell (involving, say, a man throwing his cigarette butt out of his car window into a dry patch of leaves, which given the laws of physics ultimately results in the fire). There is an explanatory story, in other words, that fully explains why what occurred did occur, that specifies how there was enough going on in reality to make the forest fire take place exactly the way that it did. There is a story, to make the point more abstractly, according to which no part of anything that occurred in the fire event popped up from metaphysical nonbeing.

Especially since the PSR is such a foundational intuition, I run the risk of confusing matters—or even raising undue suspicion about its truth—by trying to articulate the principle in various ways. If the PSR has started to sound confusing, just remember the basic formula: something cannot come from nothing. Or you might just think of it this way, keeping in mind that I am using the term “cause” in the broad sense of simply that which accounts for why something is the case: nothing is uncaused; there are no uncaused things.

3. A Cumulative Case Against the PSR

First, so the philosopher who rejects the PSR might begin, proof must be given for the PSR. But how is one ever to give such a proof?

Second, uncaused events—events that pop up from metaphysical nonbeing, things that arise from literal nothingness—seem logically possible. We can imagine, for example, a potato popping up out of the blue in the middle of the room.

Third, quantum mechanics holds that uncaused events do happen! Obviously, if things pop up in time without any objective sufficient explanation, if certain particles emerge from nonbeing (so-called “virtual particles,” for example), or if energy surges out of metaphysical nothingness, then the PSR is false. Here is how such a picture might look, in terms of two scientific examples.

(a) Assume that the past up to and including the state of physical reality at T1 makes it such that there is merely a 75% probability that a certain particle will move exactly the way that it does a split-second later. In this case, the past up to and including the state of physical reality at T1 sets up the odds and objective randomness settles the matter (such that not even God could give a complete story that accounts for why it moved exactly the way that it did as opposed to some other way).

(b) Assume that we have two exactly similar entireties of reality, both of which have a uranium atom in a certain condition at moment T. Because of the nature of the radioactive decay of uranium, it is possible for the atom to be there a split-second later in the one realm and yet not be there in the other realm without any sufficient reason for the difference. This is a change, in effect, whose happening, happening just then, not even an omniscient being like God could have foretold.

Fourth, it is standard for philosophers to describe God as uncaused. It is currently fashionable, moreover, for philosophers to buttress their theories with brute facts, facts that lack a complete explanation. Are we to believe that all these philosophers are so deeply misguided?

Fifth, saying that the uncaused category is necessarily empty, which we do if we endorse the PSR, leads straightaway to a vertiginous reality where everything is necessary (as I argued in an earlier post). Despite being virtually unavoidable even for advocates of Necessitarianism, everyday claims about how things could have gone—“you could have left earlier to avoid traffic”—make no sense in such a modally-collapsed reality. Since the PSR is less intuitive than the idea that things could have been otherwise, why not simply abandon the PSR to avoid the horror of N?

4. My Response to the First Part of the Cumulative Case Against the PSR

(1) The difficulty of providing proof for the PSR is a matter of it being such a foundational truth. To deny that everything has a sufficient explanation is to say the absurd: that being can come from nonbeing; that x can have reality even though reality—reality all-things-considered—is ultimately not enough for x to have reality. Nothing, after all, can come from literal nothing. The proof, then, amounts simply to stating the following: it is absurd to say something that has reality—some energy, some process, some thought, some action, some hallucination, some quantum fluctuation, or so on—can bloom from what lacks all reality, from what lacks absolutely any ontological oomph (even the oomph of a hallucination). Only something going on can engender something going on.

(2) In demanding that proof be given for the PSR, the opponent is demanding that a sufficient reason be given for the PSR. The opponent thereby seems to assume that for something to be the case—in this case, that the PSR is true—there must be a sufficient reason why it is the case. In short, the opponent seems to concede that the PSR is true!

(3) In a similar self-undermining gesture, opponents of the PSR who say that its advocates fail to give a sufficient reason for why the PSR is true thereby hold advocates to a standard that the opponents themselves reject: the standard that the PSR is true!

(4) Relatedly, those who oppose the PSR through argumentation attempt to give a sufficient reason why it is false, thereby seemingly endorsing it in opposing it. Any argument against the PSR tries to give a sufficient reason for rejecting the PSR and so seems to assume that for something to be the case—in this case, that the PSR is false—there must be a sufficient reason why it is the case!

(5) The PSR is so basic that one can try to prove it only by appealing to evidence equally evident as or less evident than the PSR.

(6) Explanations that rely on getting something from nothing are empty. For example, imagine that the punching bag being off the floor is explained by its chain being connected to a rod off the floor, but that there is no objective explanation—not just that we do not know the explanation—for why the rod itself is off the floor. Since the rod’s being off the floor in the first place lacks a sufficient explanation, the explanation as to why the punching bag is off the floor—namely, that its chain is connected to that rod—is empty.

(7) In addition to the fact that everyday things have explanations and behave in ways both intelligible and expected, to suppose that the PSR is false would undercut philosophy and science, which attempts to uncover the intelligibility of reality and which bears many fruits by supposing that the PSR is true.

5. My Responses to the Second Part of the Cumulative Case Against the PSR

(1) When you imagine a potato popping up in the room, you are imagining a situation where you simply do not see the full cause. You are not imagining a potato coming from nothing. After all, you cannot even imagine nothing—nothing in the true sense: not empty space or a vacuum or blackness or potentialities or field forces or a sea of fluctuating energy, but rather absolute nonbeing. Even if imagining nothing were not required for imagining something truly coming into existence out of nothing, imagining something coming into existence out of nothing would at least require doing what is beyond our reach: namely, imagining as absent every possible sort of cause for that thing—including, and this is the nail-in-the-coffin point, causes for that thing that we could not even imagine.

(2) We would not assume that a potato popping up out of thin air is a case of the potato coming into existence in the first place. We would assume, instead, that it was transported somehow—say, by teleportation.

(3) If there is any sense to saying that we can conceive of a potato popping into existence out of nothing, then we must mean that we can conceive of a potato popping into existence without a cause. But conceiving of a potato popping into existence abstracted from any cause is not the same as conceiving of it as literally uncaused, that is, as having no cause.

(4) Besides, we should question whose power to conceive is being appealed to here. A statement that is necessarily true might be conceived as false by Willy the Wino, but that does not mean that it is possible for that statement to be false.

(5) Even if by some magic something coming into existence from nothing were truly conceivable (that is, within our ability to form a clear idea of), that might not guarantee that it is logically possible (that is, involving no contradiction). Although I am unsure about the matter, there are some reasons to think that conceivability does not imply logical possibility. Here is a possible example.

Could there be a situation in which I am not the person I am? Obviously not. Such a situation would require me to be a person different than the person that I am even while I am the person that I am. There seem to be situations, however, where I can conceive that the person named by my name does not exist even while I conceive of myself as existing. Imagine, for instance, that after a blow to the head I think that the person named by my name is not me but someone else. Imagine, in fact, that I daydream about obliterating this person (say, because reports of his musical skill make me envious). Since I conceive of such a world where the person named by my name no longer exists whereas I go on living a satisfied life, here seems to be a case where I conceive myself existing without the person named by my name existing. Of course, the conceivable world where I exist while the person named by my name does not exist is not logically possible. One might say that conceivability, therefore, does not entail logical possibility.

(6) Even if by some magic something coming into existence from nothing were logically possible (possible according to logical abstraction), that perhaps would not make it metaphysically possible (possible according to reality itself, all things considered). After all, there are reasons to think that logical possibility does not imply metaphysical possibility. Consider the following example.

Assume that a unicorn never is actualized and assume also that Necessitarianism is true (such that only whatever is actualized is metaphysically possible). Even in such a world where a unicorn is, in effect, metaphysically impossible, a unicorn still seems to be a self-consistent concept and so logically possible.

(7) Even if by some magic something coming into existence from nothing were metaphysically possible, it is more reasonable that everything has a full cause than that there are things without a full cause anyway.

6. My Responses to the Third Part of the Cumulative Case Against the PSR

(1) It is a downright uniformed interpretation of quantum mechanics according to which there are uncaused events in the microworld. Electrons, for example, do not just pop into existence, despite how people sometimes speak. The electron in itself is a cloud everywhere inside the atom—a probability cloud, a wave-function, with a nature (a nature that tells us the likelihood of seeing the electron in a certain position were you to look). The wave function simply collapses when it is observed. Nothing is popping into existence out of nothing.

(2) The physicist’s sense of nothing, anyway, is not the sense of nothing with which we are concerned in philosophy: nonbeing, which appears to be both logically and metaphysically impossible anyway. Some physicists say that a universe can bloom from a quantum vacuum. A quantum vacuum, however, is—and it is something, something quite specific: it is a quantum field at a low energy state.

(3) As physicists readily admit, and to put it as Sean Carrol does, scientists do not understand what is going on in the quantum world any more than the average person understands what is going on in their smartphones. Just as the unpredictability of a random number generator is merely a matter of the complexity of its algorithm, microworld unpredictability seems to be just a matter of the complexity of what is going on (rather than a matter of genuine randomness, the randomness of something literally coming from nothing).

(4) The central interpretations of quantum mechanics are all compatible with the PSR. On the Copenhagen interpretation, the presence of an observer is one of the variables that, in concert with all the other relevant variables, provides the sufficient cause of the quantum event. On the Everett interpretation, different possible outcomes of quantum scenarios all happen (cat alive in one universe, cat dead in another) but are sufficiently caused by what is going on. On the hidden variable interpretation, all the variables relevant to bringing about the quantum event may not seem to add up to a sufficient cause of the quantum event, but that is just because we are not aware of all the variables. Contrary to what the pop interpretation holds, therefore, what is going on in reality is enough to bring about all quantum happenings that actually do happen: reality all by itself suffices for the particle moving exactly how it does move (contrary to the first objection-example); reality all by itself guarantees that the atom is decayed at a given time if it is decayed, and reality all by itself guarantees that the atom is not decayed at a given time if it is not decayed (contrary to the second objection-example).

(5) Causes may be hard to discover, and may involve great complexity, but it seems strange for scientists to assert that in some cases there is no cause whatsoever. It could be said that scientists do precisely that in the case of the big bang. But even if that were true, which it is not (since a quantum vacuum, with its fields and energy fluctuations, is not literally nonbeing), it would seem more in line with the anti-dogmatic spirit of science to conclude that we do not know the full explanation (rather than that there definitely is no full explanation). The currently unexplained need not be the absolutely inexplicable—inexplicable in the sense of having been emitted, so to say, from nonbeing.

(6) There is no way that beings coming from nothing—nonbeing flares, if you will—can ever be demonstrated experimentally, for obvious reasons.

(7) We would be hard-pressed to find, especially in light of the previous point, any scientist who (a) understands the being-from-nonbeing implication of something lacking a sufficient cause and yet who (b) says that a certain event lacks a sufficient cause. As in when someone says that the universe comes from nothing in the sense of coming from a quantum vacuum, any scientist who speaks of an event lacking a sufficient cause is—so at least should be the default interpretation as a matter of charity—not speaking in the strict context of the philosophy classroom.

(8) What is the greater miracle anyway: that a certain event E lacks a sufficient cause or that the scientists who claim that E lacks a sufficient cause are simply not aware of the sufficient cause? Especially since scientists are finite and fallible, the greater miracle—and so the one to be rejected—is that E lacks a sufficient cause.

7. My Responses to the Fourth Part of the Cumulative Case Against the PSR

(1) There is no substantial discrepancy, upon reflection, between the common description of God as uncaused and my claim that the PSR is true and thus that the uncaused category is necessarily empty. We must be careful, so the great 17^th century rationalists like Spinoza and Descartes tell us, to distinguish between something being self-caused, that is, being brute in the virtuous sense of existing by the necessity of its own nature, and something being uncaused, that is, being brute in the vicious sense of having reality despite reality ultimately failing to be enough for it to have reality. Unless one slurs over such a difference, or unless one assumes that cause must come prior to effect such that self-causation is a nonstarter absurdity, or unless one take the claim that “everything has a cause” to be nothing more than the claim that “everything is other-caused,” no one strictly speaking is going to call God either “uncaused” or “other-caused” since both options mean that the very being of God is received, if you will, from non-God. Even that which always already is we are not going to call “God,” strictly speaking, if it just so happens that it always already is. Instead, and as Descartes and Spinoza make clear, one is going to call God “self-caused”: that which is the adequate immanent condition of itself, that which is the non-explanatorily-prior determining principle for what and that it is, in the sense of having an essence that involves existence—having an essence that involves existence, but not merely in the sense that the being with that essence just so happens to exist.

To be sure, Aquinas (and almost every theologian in his wake) see things through a lens according to which it is inappropriate to call God “self-caused.” But these thinkers have in mind the two repugnant senses of self-causation described in an earlier post (that is, either a thing existing before it exists in order to cause itself to exist or a thing causing itself to exist at the very same moment it comes to exist in the first place) and they construe God’s being uncaused in the way that the great rationalists, who rightly cannot countenance anything lacking a sufficient reason, construe God’s being self-caused: namely, God’s not being other-caused and so God’s existing eternally by the necessity of God’s own nature. In effect, the disagreement between Aquinas (and his followers), on the one hand, and Descartes (and his followers), on the other, is largely verbal. For reasons that should be clear by now, however, I find the Cartesian way of speaking more precise. After all, talk of God being causa sui­ is, as Jerome makes clear in his commentary on Ephesians 3:15, a way to highlight God’s aseity while honoring the deep principle that nothing comes from nothing and the deep intuition that God, in particular, cannot be thrown into this, like this—even thrown into this, like this, from eternity—in a way not up to him.

(2) However fashionable it may be to pull brute-fact cards in philosophy, any view that relies on something having being ex nihilo—having being ex nihilo, remember, in a sense that does not mean that it has being from itself—is a nonstarter absurdity. But aside from that, there are various reasons why the prevalence of brute-fact-card pulling in contemporary philosophy does not count against the PSR as much as it might seem too. 

(a) The notion of bruteness is ambiguous. On the one hand, there is bruteness in the virtuous sense: the PSR-friendly sense of being sufficiently self-explained (self-caused). On the other hand, there is bruteness in the vicious sense: the PSR-unfriendly sense of having objectively no explanation (uncaused). The difference between the two senses of bruteness is important. One does not just get to pull the virtuous brute-fact card. Indeed, it does not even seem right to call it a “card.” Unlike in the case of pulling the vicious brute-fact card, pulling the virtuous brute-fact card has to be warranted by positive evidence (positive evidence for something existing by the necessity of its own nature) and does not entail the manifest repugnancy of saying that something obtains even though reality ultimately fails to suffice for it obtaining.

Why bring all this up? Well, some of those said to be pulling brute-fact cards may not be pulling vicious brute-fact cards. It is common to find theists faced with the objection that they pull a brute-fact card at God. It is common, in turn, for opponents to claim that pulling a brute-fact card at, say, the big bang is no worse than pulling a brute-fact card at God. “If we must stop the chain of explanation somewhere,” so goes the reasoning, “why not stop it in a place that preempts the need for God?” What the objector does not realize is that the theist is—or at least should be—pulling a virtuous brute-fact card, one that does not involve a commitment to getting something from nothing. So aside from just the normalization of brute-fact-card pulling, the failure to disambiguate between these two senses of bruteness, together with it being “common knowledge”—one of the ta legomena in our culture—that the PSR is false if there are brute facts (and so nothing we have to interrogate further), makes it seem that there are more philosophers out there rejecting the PSR than actually are (or that actually would, upon scrutiny).

(b) Even if the numbers are not so high as one would think in light of the above ambiguity, it would be foolish to deny the pervasiveness in contemporary philosophy of pulling brute-fact cards in the vicious sense. But something else that should be kept in mind is the language philosophers use. Rarely if ever will someone who pulls a vicious brute-fact card say to themselves or others: “I am pulling a getting-being-from-nonbeing card.” At best they might say “I am pulling a free-lunch card” or “such and such is true merely by fiat” or so on. Just as euphemisms concerning the dying process can cloak what is really involved in the dying process, talk of “brute facts” is euphemistic enough to cloak what is really entailed by pulling a vicious brute-fact card. Especially when repeated in articles and at conferences in good conscience (and as if no bigger deal among philosophers than steroid use is among bodybuilders), talk of “brute facts” and “free lunches” sounds much more harmless than PSR-unfriendly talk of something coming from nothing. Indeed, talk of “brute facts” and “free lunches” might be confusable—especially for philosophers just starting to bud—for PSR-friendly talk of what is merely beyond our current ability to explain. So aside from just the normalization of brute-fact-card pulling, the euphemistic and vague language of “brute fact,” together with it being “common knowledge”—one of the ta legomena in our culture—that the PSR is false if there are brute facts (and so nothing we have to interrogate further), might be blinding people to what is actually at stake in rejecting the PSR and making it seem as if there are more philosophers out there rejecting the PSR than actually are (or that actually would, upon scrutiny).

8. My Responses to the Fifth Part of the Cumulative Case Against the PSR

(1) Even if the PSR entails Necessitarianism, which I have argued it does in an earlier post, endorsing a view that rocks our identities and spells modal collapse is better than accepting what seems an absolute nonstarter: getting something from nothing. The principle that things could have been otherwise is intuitive, no doubt. Indeed, many might find it more intuitive than the PSR at first glance. It is hard to fathom, however, how anyone could find it more intuitive than the PSR once they penetrate the euphemistic veil with which the denial of the PSR is often cloaked and once they grasp what denying the PSR amounts to: that being can be excreted out of nonbeing. (This is a matter for experimental philosophy, of course. For whatever it might be worth, however, everyone I poll either finds the PSR more intuitive or finds the two principles at least equally intuitive.)

(2) Talk about how things could have been otherwise still makes sense even if Necessitarianism is true. Saying “I could have worn a green shirt instead of a red shirt today” means, so the advocate of Necessitarianism is happy to allow, that I would have worn green had conditions been different in a certain way. To be sure, it is impossible (at least in some sense) for those conditions to have been different in that certain way. But that does not mean it is nonsense to talk about what would have been if—if, of course, per impossibile (at least in some sense)—those conditions were different in that certain way. That is perhaps all that needs to be said.

One might wonder, however, why I use the language of “impossible at least in some sense”? To lay out a picture that is compatible with the PSR and even with Absolute Necessitarianism (the view that there is an ultimate reality that provides the determining condition for itself and whatever else there may be), let us imagine that the “possible worlds” we talk about in metaphysics are all “out there,” concrete and independent of one another (each its own “windowless” monad, so to say). It is possible, in such a plenitudinous reality of various maximally-inclusive concrete worlds, for conditions to be different in our world, W1, at least in the sense that there is some other world, W2, where they are different. For reasons stated at the outset, advocates of Necessitarianism need not endorse a reality of concrete alternative universes to explain how N’s truth fails to render meaningless our talk about how things could have been otherwise. It is important to point out, however, that endorsing such a reality allows advocates of Necessitarianism to honor, on the one hand, their position that what is possible is merely what obtains all things considered and, on the other hand, the deep intuition—often regarded as incompatible with N—that more is possible than what ends up obtaining in our universe, W1.

This piece is unpublished

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