Sunday, May 13, 2012

The Leibnizian Cosmological Argument for God (Page 2)

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The Leibnizian Cosmological Argument for God
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The Argument (LCA 1A)
  1. Everything that exists has an explanation of its existence, either in the necessity of its own nature or an external cause.
  2. The universe exists.
  3. If the universe does have an explanation for its existence, that explanation is God.
  4. Therefore, the universe has an explanation of its existence (from 1 and 2).
  5. Therefore, the explanation for the existence of the universe is God (from 3 and 4).
Justifying Premise 3

What about premise 3? That looks like it would be controversial, but it’s not as controversial as one might think. If the atheist believes the PSR is false with respect to the universe and that the universe has no explanation of its existence (which is perhaps the most popular atheist response to the LCA) then justifying premise 3 is relatively easy. Such an atheist believes the universe has no explanation of its existence, and thus believes that “If God does not exist then the universe has no explanation of its existence” is true. But “If God does not exist, then the universe has no explanation of its existence” is logically equivalent (to the point where one could prove it is so equivalent using symbolic logic) to “If the universe has an explanation of its existence, then God exists.” So if “If God does not exist, then the universe has no explanation of its existence” is true, then so is “If the universe has an explanation of its existence, then God exists,” which is almost synonymous with premise 3. In traditional theism, God is the external cause of the universe.

What if the atheist believes the PSR is true with respect to the universe and that the universe has an explanation of its existence? Beyond “there is no explanation for why the universe exists” being a very popular atheist response, there is good independent reason for thinking that “If God does not exist, then the universe has no explanation of its existence” is true. Why? Since the universe is all of physical reality, what explanation could there be for it if the PSR (premise 1) applies to the universe? We have two options: (1) the explanation of the universe lies in the necessity of its own nature; or (2) the universe has an external cause of its existence. First let’s examine option (1).

Physical reality doesn’t seem to be the sort of thing that exists necessarily. There doesn’t appear to be any physical part of physical reality that is metaphysically necessary (e.g. stars and planets are contingent and indeed at one point they failed to exist; there are also no molecules that couldn’t fail to exist) and with that in mind consider the following argument from subtraction. Is a universe with only a thousand physical things possible? It seems so. How about a hundred? Sure. How about ten? How about five, four, three, two, and one? How about none? It seems like there is some possible world where no physical reality at all exists. (Notably, if nothing existed at all, this would fit in with the PSR since if literally nothing exists then there isn’t anything to explain.) The subtraction pattern, followed to its logical end, suggests that physical reality didn’t have to exist. One could claim that the subtraction pattern works all the way down to one physical thing existing (let’s label that one physical thing item #1) at which point no further subtraction is metaphysically possible. But since every physical thing is contingent including item #1, some justification is required to prevent this claim from being a mere ad hoc maneuver. If there is a possible world where no physical reality at all exists, then a fortiori there is a possible world where our own physical universe does not exist, in which case the explanation of the universe’s existence cannot lie in the necessity of its own nature because the universe does not have necessary existence.

Suppose though we grant that some type of physical reality or other must exist. There’s still the problem of explaining why this physical universe exists. Before explaining how that works, first some preliminaries. Let’s call the most basic, elementary stuff of physical reality (whether it be strings, quarks, some additional particles etc.) “fundamental units.” Let the Alice universe consist of only the fundamental units of Alice’s body and the Bob universe consist only of the fundamental units of Bob’s body. Both the Alice universe and the Bob universe seem to be possible worlds (think of the argument from subtraction; we could subtract everything but the fundamental units of Alice’s body etc.). The Alice universe consists of an entirely different set of fundamental units than the Bob universe; thus these are two different universes, just as two wooden sculptures would be different sculptures by each being made from a different tree. But then couldn’t the physical universe we live in (call it Kronos) similarly have had at least some of its fundamental units be different units? Couldn’t the universe have had a different set of such units? We can even conceive of a physical universe that has an entirely different set of fundamental units than Kronos (call this universe Rhea). The Alice and Bob universes have entirely different sets of fundamental units making them different universes, likewise Kronos and Rhea are different universes due to being composed of different fundamental units. So even if it were true by metaphysical necessity that some physical reality or other exist, it would still be the case that the Kronos universe is contingent (since the Rhea universe is also possible; indeed there even seem to be possible worlds with very different physical laws that don’t even have quarks, photons, etc.), in which case the PSR demands that the Kronos universe, being contingent, has an explanation of its existence that isn’t the necessity of its own nature.

With option (1) being untenable, let’s consider explanatory option (2): the universe having an external cause of its existence. If we go the explanatory route of some external cause of the universe, an external cause of all physical reality would have to be nonphysical, and there are only two sorts of things we know of that could fit requirement: abstract objects (like numbers) and unembodied minds (e.g. God, if he exists). But abstract objects can’t cause anything. So the only viable candidate for a nonphysical cause seems to be a personal cause. Among the pool of explanatory options considered (the universe existing by the necessity of its own nature, physical things causing the universe, abstract objects causing the universe, and a transcendent personal cause of the universe) a transcendent personal cause is by far the best explanation; indeed it is the only viable explanation among the entire pool. Thus we’re left with a transcendent personal cause of the universe if the universe has an explanation of its existence.

It bears remembering that if we grant that the universe has an explanation of its existence, the external cause of the universe cannot be a physical cause and must be nonphysical. This is quite notable, because if the correct explanation isn’t God creating the universe, it would have to be something no less strange than that (e.g. another sort of unembodied mind or a quartet of unembodied minds). But when discussing a nonphysical external cause, the only live options for nonphysical entities were abstract objects and unembodied minds, and the critic could say maybe there’s a third sort of nonphysical thing that nobody has ever even thought of (the critic gives no details as to what this cryptic nonphysical thing could be apart from it being neither an abstract object nor a mind and it somehow causing the physical universe) and perhaps this sort of unknown nonphysical thing being the external cause of the universe is an even better explanation of the universe’s existence than a transcendent personal cause. One problem with that response: the bare possibility of an unknown alternate explanation seems insufficient. Suppose for example I meet an evolutionary biologist and I say we should not accept evolution as an explanation. The biologist asks me for a better causal explanation for the diversity of life we see, and I reply maybe there’s a possible cause that nobody’s ever thought of (I give no details beyond this cause being physical and not evolution) that is both the actual cause and a better explanation than evolution. The evolutionist will rightly see this as insufficient grounds for rejecting the evolutionary explanation. Similarly, the bare possibility of some unknown alternative is insufficient for rejecting the explanation of a transcendent personal cause. The idea that there is some other sort of nonphysical entity that nobody’s ever thought of that can create universes is not a viable option if the only thing one can describe of it is that it’s not an unembodied mind nor an abstract object. If that were enough to qualify for a viable explanation, then we have also have a viable alternative explanation to evolution (an unknown physical cause that is not evolution causing various data that evolution explains). All things considered, “If the universe does have an explanation for its existence, that explanation is a transcendent personal cause” is more plausible than its denial.

If I were an atheist, I would believe “If the universe does have an explanation for its existence, that explanation is a transcendent personal cause” is true and to avoid the conclusion I would instead believe that the universe just exists inexplicably and eternally with no external cause of its existence. Would a transcendent personal cause of the universe prove theism true with absolute certainty? No, but knowing that there is a transcendent personal cause of the physical universe would make atheism much less plausible. All things considered then, “If God does not exist, then the universe has no explanation of its existence” seems very likely true, which thus gives us very strong grounds for accepting premise 3.

Still, if the atheist insists that God is not a legitimate explanation (for whatever reason) or that the justification still isn’t good enough for the third premise (despite “If God does not exist, then the universe has no explanation of its existence” apparently giving us such justification to believe premise 3) we can bypass these concerns and construct the following argument instead (call it LCA 1B).
  1. Everything that exists has an explanation of its existence, either in the necessity of its own nature or an external cause.
  2. The universe exists.
  3. If the universe does have an explanation for its existence, that explanation is a transcendent personal cause.
  4. Therefore, the universe has an explanation of its existence (from 1 and 2).
  5. Therefore, the explanation for the existence of the universe is a transcendent personal cause (from 3 and 4).
The conclusion isn’t “God exists,” but as I noted earlier, that there is a transcendent personal cause of the physical universe would still make atheism considerably less plausible.

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Comment on this article

4 comments:

  1. In case you ever get back to this, premise 3 is false. Your argument that the "unknown hypothesis" is not a credible alternative to evolution is true but for the wrong reasons. The reason we accept evolution is because there is a massive amount of evidence that supports it, it has nothing to do with how plausible the hypothesis sounds or because there are no competing hypotheses.

    Even if there were no alternative hypotheses, a good scientist (and logician) should not assume that the single remaining hypothesis they have is correct (or probable) unless he or she knows that there are no other unseen alternatives.

    In this case, the latter seems impossible to demonstrate unless you can somehow argue that your brain understands everything outside of our universe with 100% certainty. Clearly you don't - hence unseen alternatives are entirely possible. Hence you can't assume that the hypothesis you have (the God hypothesis) is correct by deductive logic. Hence it remains speculative and unproven.

    Remember, an idea is not valid, or assumed to be valid, simply because it explains something. To be valid you need a reason to believe that the idea is actually represented in reality. There have been many valid ideas in science that explained natural phenomena, as well as a plethora of Gods that have been dreamed up by ancient people. I don't need to tell you that they have all been wrong. Your article is just a continuation in a long line of speculative assumptions which were given too much power for no good reason. I am a little disappointed that a fellow atheist somehow is not aware of the basic scientific method though.

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    1. (And by fellow atheist I refer to Maverick Atheism).

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