“the abyss that separates any conflicting philosophical systems precludes any use of argumentum ad rem; for to appeal to evidence in attacking a position that claims to include all the evidence is to beg the question. Thus every valid philosophical argument is ad hominem.” -Johnstone Jr.
followup (Perry) - ‘This may be why every beginning philosophy student is told what happened to Socrates, judged to deserve destruction. The poison hemlock he was given to drink was literally an ad hominem attack, the same as the instruments of torture shown to Galileo, the same as Auschwitz.’
here’s the link i got it from http://www.bu.edu/wcp/Papers/Teac/TeacPerr.htm