It is said that clothes can be hung but men are hanged.
Is this correct, and if so, why?
According to the OED, the verb hang came into English from Old Norse hengja with weak inflection (so, taking regular past forms). Eventually, by analogy with other ablaut forms like sing/sang/sung, the verb hang changed into a few different forms (depending on the region of England), e.g. hing/hang, hang/hong, etc. Ultimately, the hing/hang form added hung to complete the sing/sang/sung analogy.
Now here's the important bit, directly from the OED:
(At some point, obviously hing fell out of use in Standard English in the present tense form.)
This old reference in the Dictionary of the English Language (thanks, Google Books!) supports the usage you outline as correct.
Grammar Girl writes that this is because there are 2 different Old English words for the two meanings.
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