Aug. 24., 2012 | 12:20 pm
No:: begemots
They say it comes from the medieval Latin aphorism Exceptio probat regulam. Probat means "prove" in the sense of "test," as in "proving ground" or "the proof is in the pudding." So "the exception proves the rule" means a close look at exceptions helps us determine a rule's validity.
If Latinists understand it that way, however, they're pretty much alone. I've looked up citations of this saying dating back to 1664, and in every case it was used in the brain-dead manner we're accustomed to today — that is, to suggest that non-conforming cases, by the mere fact of their existence, somehow confirm or support a generalization. Obviously they do nothing of the kind. We like to think proverbs become proverbial because they're true; this one is an exception. It certainly doesn't prove the rule.
http://www.straightdope.com/columns/rea
If Latinists understand it that way, however, they're pretty much alone. I've looked up citations of this saying dating back to 1664, and in every case it was used in the brain-dead manner we're accustomed to today — that is, to suggest that non-conforming cases, by the mere fact of their existence, somehow confirm or support a generalization. Obviously they do nothing of the kind. We like to think proverbs become proverbial because they're true; this one is an exception. It certainly doesn't prove the rule.
http://www.straightdope.com/columns/rea