Notes on the Principle of Sufficient Reason

– It was pointed out that most arguments from contingency rely on some version of the principle of sufficient reason. This is broadly true.

– Broadly (again), the PSR can be boiled down to the idea that for every true proposition, there is a sufficient reason for its truth. A somewhat different interpretation:

‘The principle holds that nothing takes place without a reason; for any occurrence, a being with sufficient knowledge would be able to give a reason sufficient to explain why it is as it is and not otherwise.’ (‘ Dictionary of Philosophy and Religion, p. 299)

– So, basically, it’s concerned with contingent states of affairs – why this, and not that kind of thinking. That’s pretty obvious – if it is the case that an occurrence could have been otherwise, it’s contingent. That’s pretty much the definition of contingent.

– It appears that, at first glance, the PSR stumbles when it comes to things like necessary truths. If the PSR applies to contingent propositions/events, what about necessary ones (I realize I’m mixing propositions/events, but you get the idea)? Or even the PSR itself? Is it just a brute fact? Put another way, why accept the PSR?

– Leibniz held that for necessary truths/propositions, their negation is a contradiction – and that this was the sufficient reason .

– Perhaps as a law of thought or a law of logic, rather than an existential ontological theory, it’s more solid. As an ontological theory it basically ends up being a causal argument – everything that begins to exist has a cause. This has the curious property of being a tautology, though – of something begins to exist, then by definition it has a cause. So it seems that it’s trivially true, which isn’t terribly helpful.

– But as a logical law, it seems better. It is the case that for every true proposition, there is a reason why it’s true makes more sense and is a bit less tautological. If something is true, then there is an explanation as to why it is true.


One thought on “Notes on the Principle of Sufficient Reason

  1. Chris Falter October 6, 2014 / 12:36 pm

    HI Josh,

    As always, a thought-provoking read. As a practical matter, I wonder how helpful the PSR is. It posits that a being with sufficient intelligence can explain everything that is, but so many facts in the universe defy the limits of our human understanding! In other words, the only Being with sufficient intelligence to explain many key facts has chosen to give us the opportunity to live by faith, rather than sharing comprehensive explanations with us. Probably we couldn’t handle it, but that’s another discussion.


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