Why would someone pay $959,500 for a used guitar?

That was a difficult enough question in 2004 when Eric Clapton sold his beloved Fender Stratocaster named Blackie. But now, as collectors around the world prepare to bid Wednesday at another charity auction of Mr. Clapton’s guitars, the questions are even tougher.

Why would someone create a replica of Blackie, complete with every single nick and scratch, including the wear pattern from Mr. Clapton’s belt buckle and the burn mark from his cigarettes? And why is that replica expected to fetch at least $20,000 at Wednesday’s auction, and probably much more?

Fortunately, social scientists have been hard at work on the answers. After conducting experiments and interviewing guitar players and collectors, they have just published papers analyzing “celebrity contagion” and “imitative magic,” not to mention “a dynamic cyclical model of fetishization appropriate to an age of mass-production.”

One of their conclusions is that the seemingly illogical yearning for a Clapton relic, even a pseudorelic, stems from an instinct crucial to surviving disasters like the Black Death: the belief that certain properties are contagious, either in a good or a bad way. Another conclusion is that the magical thinking chronicled in “primitive” tribes will affect bids for the Clapton guitars being auctioned at Bonhams in Midtown Manhattan.