In “Anti-ID Philosopher: “Ad Hominem” Arguments “Justified” When Attacking Intelligent Design Proponents” (Evolution News & Views, June 4, 2012), Casey Luskin reports,
In 2008, philosopher Jeffrey Koperski published a fine article in the religion and science journal Zygon in which he argued that ad hominem attacks are a “bad way” to critique proponents of intelligent design. Why? Largely, he wrote, because they entail a logical fallacy — the genetic fallacy. That is, they address the origin of an argument rather than the argument itself. Now, Christopher A. Pynes, an associate professor of philosophy at Western Illinois University, has written a reply to Koperski. According to Pynes, contrary to the normal rules of respectable scholarly discourse, it is permissible to engage in ad hominem attacks — provided that you are attacking proponents of intelligent design.
The reason for this exception to the standard rule against logical fallacies, Pynes argues, is on account of the motives of ID’s proponents.
More. Luskin offers considerable evidence of the atheist sympathies of the current evolution establishment, 78% of whom are pure materialist atheists.
In any event: Ad hominem argument is always a bad way of making a decision because the relevance of information may be unrelated to how you come to hear it. But it is always related to how well it accounts for the evidence.