Peirce and the Principle of Sufficient Reason

Posted on June 25, 2008
Filed Under Philosophy |

Over at Brood Comb Tanasije has an interesting argument for the principle of sufficient reason. It got me to thinking of Peirce since there are some parallels in Tanasije’s argument. (I don’t think it works mind you if only because of a vicious regress that I think Heidegger points out) What I wanted to mention though was how the principle ends up being so important for Peirce.

For both Leibniz and Wolff the principle was more than just a principle of logic it was also a principle of metaphysics. (Often the metaphysical aspects of their logic is overlooked when people read them) For them any affirmative non-identical true proposition a ‘reason’ must exist that allows the proposition to be demonstrated in a syllogism.

The so-called first figure syllogism involves a subject - predicate relationship for each step and then a major premise, minor premise and conclusion.

Subject Predicate
Middle Term Major Term Major Premise
Minor Term Middle Term Minor Premise
Minor Term Major Term Conclusion
Example:
C is B
A is C
Therefore A is B

This kind of syllogism demonstrates or shows why something is so. In this tradition (which admittedly is pretty alien to us today) the middle term is what establishes the connection between the subject in the minor premise and the predicate in the conclusion.

The implication from all this for Leibniz and Wolff is that there must be a principle of continuity since for any case there must be a middle term.

Peirce took this and ran with it. It forms part of his conception of infinity and continuity. (For Peirce called synechism) It was one of his three basic categories of phenomenology: thirdness or the idea that everything is mediated.

Comments

One Response to “Peirce and the Principle of Sufficient Reason”

Brian Weatherson has a great post on the PSR as well. He questions whether we ought distinguish between “every truth has an explanation” from whether “every truth is explicable.” It’s a very interesting point that I think ends up raising the question of whether there are coincidences. Of course Leibniz as a good determinist would have said there aren’t coincidences. But if we reject determinism how does that affect the PSR?

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