Relativity had little to do with the development of the atomic bomb.

An ad hominem argument (as a fallacy) is one which seeks to discredit the speaker of an argument rather than the merit of the argument itself.

If the character of a person is one of the _substantive arguments_ bearing on a debate, as in a court case, than discussion of his character is not, in this sense, an ad hominem argument, but rather an argument in res hominem, about the subject of the person. If you asserted that the person's lawyer was a weaselly son of a bitch who should not be believed for two nanoseconds and who would sell his mother for the price of a beer --- _that_ would be an ad hominem argument.

A