ad hominem

from WordNet (r) 3.0 (2006)

ad hominem
    adj 1: appealing to personal considerations (rather than to fact
           or reason); "ad hominem arguments"

from The Collaborative International Dictionary of English v.0.48

Ad hominem \Ad hom"i*nem\ [L., to the man.]
   A phrase applied to an appeal or argument addressed to the
   principles, interests, or passions of a man.
   [1913 Webster]