The laws of logic are believed to be the basis of rational thought. But what grounds logic itself? Surely logic cannot be grounded in logic, for that would be circular reasoning, and therefore illogical. Yale Professor Jacob McNulty argues there is no logical foundation for logic. Instead we should look to Hegel for a solution to this dilemma, according to which logic is derived from metaphysics.
Consider logic, the area of philosophy traditionally tasked with identifying the most basic inviolable laws of rational thought: for example the law of noncontradiction; or modus ponens (“if p, then q” “p” therefore “q”). What justification could one give for logic? The question leads to a dilemma.
One horn of the dilemma is vicious circularity. Suppose the justification we give takes the form of an argument. But logic’s laws are presupposed by every rational argument. Hence, any argument we might give for them would be viciously circular.
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One thing is clear: the law of noncontradiction is not self-evident.
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The other horn is complacency. Having abandoned the way of rational argument we might pursue an alternative form of justification: the way of self-evidence or brute fact. This is essentially the method Aristotle tried. He suggested that we could simply dismiss anybody who questioned the law of noncontradiction. This second approach is by far the more common in the history of philosophy (and today). Yet this type of justification also leaves something to be desired.
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