Analytical philosophy has made great progress over the last century. But its original, necessary biases did some harm, too. In particular, detailed working knowledge of the history of philosophy and metaphysics was banished for several generations. While metaphysics is thriving again, we still lack (despite the brilliance of David Lewis' modular approach) complete systems of thought that can rival in depth and interlocking breadth the past masters (say, Suarez, Leibniz, etc.). The damage has also been more narrow. For example, one of the most obvious so-called ‘Kuhn Losses’ is our relative ignorance of the nature and implications of the Principle of Sufficient Reason (PSR). This is no surprise because analytical philosophy was founded in the act of rejecting PSR. Our forefathers’ attempt to balance between common sense and the truths of science meant -- as science and the PSR parted ways -- the willing submission to brute, ultimate facts (recall this post).
In Mind & Cosmos, Thomas Nagel happily embraces “a form of the principle of sufficient reason” (17) in support of his "common sense" (5, 7, etc.) and against the recent “orthodox scientific consensus.” (10; 5) Rather than accepting this "ideological consensus," (128) Nagel insists -- regularly using language reminiscent of the great Feyerabend -- that "almost everyone in our secular culture has been browbeaten into regarding the reductive research program as sacrosanct." (7) While Nagel insists that the champions of scientific enlightenment are bullies, he treats the "defenders of intelligent design" with "gratitude" (Plantinga returns the gratitude), even though Nagel clearly recognizes that once one embraces one's inner sensus divinitatis one is also compelled in one's judgments. (12)
A classic statement of the PSR is Spinoza's "For each thing there must be assigned a cause, or reason, both for its existence and for its nonexistence." (Ethics 1p11d2) That is to say, any PSR worth having imposes significant explanatory demands (especially of non-arbitrariness) on any philosophical system in which it is deployed. Below the fold I critically discuss Nagel's way of combining the PSR and his attempted revisionary science, but here I just register the marvelousness of Nagel's deployment of the PSR as an instrument in the service of common sense! (cf. 91-2) This is certainly an original move in the history of metaphysics--one that, in a single, magical stroke overturns Lovejoy's long narrative.