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Why Everything Must Have a Reason for Its Existence

Thinking Man

NOTE: Today we feature a guest post from Steven Dillon, one of our regular commenters. When Strange Notions launched in May 2013, Steven didn't believe in the monotheistic conception God. Although he still rejects God as Trinity, he has since come to believe in a single, simple, perfect, immutable God. Today he shares one reason that swayed him closer to monotheism.

I’ve spent a lot of time arguing against theistic conclusions here, but I feel it’s time to change gears. There are a lot of good arguments out there not only for theistic sorts of beliefs (such as in an after-life), but also for God’s existence, and I’d like to start defending some of these, especially for the latter.

Now, more often than not, philosophical arguments bottleneck our rich background beliefs and experiences in such a way that our evaluations of and discussions about these arguments are just summaries of more expanded positions we hold. This prevents dialogues and debates from really changing people’s minds a lot of times because there tend to be a lot of relevant points and assumptions that go unaddressed and unexamined.

So rather than defend an entire argument for God in one post, I’d like to defend an important proposition that can play the role of ‘premise’ in various arguments for God’s existence, namely, “If anything whatsoever exists, then it has an explanation of its existence, either in the necessity of its own nature or in an external cause.” Let’s abbreviate it to “If anything exists, it has an explanation of its existence” and call it ‘PSR’ for ‘Principle of Sufficient Reason’.

PSR strikes a lot of people as pretty obvious. But, is there any evidence for it? Not only do I think there is, but I think it’s extremely difficult to deny that there is: the very existence of something counts as evidence of its explicability!

Probability theory tells us that something (call it ‘E’) counts as evidence for one hypothesis (‘H1’) over another hypothesis (‘H2’), if and only if E is more likely given that H1 is true than that H2 is.

But, something is more likely to exist given that it has an explanation of its existence (H1) than that it does not (H2), because having an explanation of its existence entails that it exists, whereas lacking such an explanation does not.1 In other words, H1 predicts that E exists better than H2 does because it entails E.

Note that we can talk about ‘things’ lacking an explanation of their existence without having to say they exist: unicorns have no explanation of their existence because they have no existence to explain.

Now, if it’s true of anything whatsoever that it is more likely to exist given H1 than H2, then it is true of anything whatsoever that if it exists, there is evidence that it has an explanation of its existence, for the two are just different ways of saying the same thing.

You might wonder how strong this evidence is: does it prove PSR, or just barely support it? As Dr. Pruss explains:

“According to the Expectation Principle [i.e. the leading philosophical interpretation of ‘likelihood’], if an event or state of affairs is more to be expected under one hypothesis, h1, than another, h2, it counts as evidence in favor of h1 over h2 – that is, in favor of the hypothesis under which it has the highest expectation. The strength of the evidence is proportional to the relative degree to which it is more to be expected under h1 than h2.”2

So the strength with which something’s existence is evidence for its explicability is just a function of how much more its existence is to be expected given that it explicable than that it is not.

Now, we know that something’s existence has the highest possible expectation given H1 because it is properly entailed or necessitated by it. As such, unless a thing’s existence is extremely expected given its inexplicability, it will count as significantly strong evidence for its explicability.

But, why should the failure of anything to have an explanation of its existence lead us to expect that it exists? The mere lack of an explanation of thing’s existence provides no reason whatsoever to think it exists because it does not in and of itself explain why there is such a lack of explanation: it could just be because there is no existence to explain.

Thus, the existence of anything whatsoever is far more to be expected given its explicability than not, and as such, we have significantly strong evidence for PSR.

Note that even if I have overestimated the strength of this evidence, it is still evidence
(Image credit: Mother Fitness)


  1. In standard probability notation: P(Something exists|It has an explanation of its existence) > P(Something exists|It does not have an explanation of its existence).
  2. William Lane Craig and James Porter Moreland, The Blackwell Companion to Natural Theology (Chichester, U.K.: Wiley-Blackwell, 2009), 206
Steven Dillon

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Steven Dillon is a nature loving hippy who enthusiastically supports the Philosophy of Religion, and the importance of good-willed dialogue between theists and atheists.

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