Bite-sized Research Series: The Dog is Not Valid

Lunch will be provided

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Suppose the following two sentences are true:
Amina is either sleeping or working.
Amina is not working.

It would seem to follow that this sentence is also true:
Amina is sleeping.

This line of reasoning -- roughly, that if 'p or q' and 'not q' are both true, then 'p' must also be true -- is known as disjunctive syllogism. Chrysippus, a third-century BCE philosopher famous for laughing himself to death, was convinced the inference was so basic that even his dog could be seen performing it. Because of this, the inference is actually sometimes just called 'the dog'.

I will argue that the dog is not valid. I will do so by carefully examining what validity requires. I will end by arguing that despite being invalid, we ought nonetheless endorse the dog when we're going about our theory building, because doing so helps us build elegant, simple, and informative theories.

(p.s. If you're into jargon (or just want to sound smart with your friends), the talk is a defense of a broadly enthymematic account of the role of disjunctive syllogism. Also important: the talk will feature pictures of cute dogs. You've been warned.)

About the Speaker: 

I grew up in Western Montana. So I didn't have to parallel park until college, which was at Gonzaga University. My wife, who I met there, taught me how. Eventually we both went to graduate school at the University of Minnesota. Since then I've had jobs here at NCSU, at Smith College, and at the University of Connecticut.