Those who are familiar with what I write are aware that I have strict standards for avoiding ad hominem arguments. In my view, we are poorly situated to understand the motives and character of other people, and so we should stick to the issues and avoid casting aspersions on the character of those whose views we oppose. Some people think this is a matter of niceness, but I see it rather as a way of keeping discussion productive.
I think one example where a lot of people with whom I sympathize made a mistake in this direction was the various responses made by critics of the original edition of John Beversluis's C. S. Lewis and the Search for Rational Religion, published in 1985. As a Lewis defender, I was sympathetic to the content of their criticisms. At the same time Richard Purtill, for example, implied that Beversluis was being deliberately dishonest in his treatment, for example, of Lewis's A Grief Observed. Now, having written a book that was harshly critical of a highly regarded Christian thinker such as Lewis, he could expect harsh criticism in return. But I do think that moving from a critique of the contents of his treatment of Lewis to a discussion of his motives and character was misguided.
Now, of course, Beversluis wrote his 2007 revision of the book, this time with Prometheus Press as opposed to Eerdmans, and he there responded to various critics of his work. Just recently, Thomas Talbott has written a reply to Beversluis's revised edition, claiming that Beversluis badly misinterpreted his defense of Lewis's treatment of the problem of evil. I linked to it a few posts back. However, Talbott's essay, as it appeared when I linked to it, did contain some aspersions against Dr. Beversluis's character, and Beversluis e-mailed me to point out that Talbott's rejoinded did not meet what he knew to be my standards of ad hominem avoidance.
I sympathize with Talbott, and am inclined to agree that Beversluis committed some serious errors in interpreting his essay. (Interestingly enough James Petrik, who independently wrote an essay which made a number of points that are similar to those of Talbott, also complained about how his essay was interpreted by Beversluis, and I heard from him before I heard from Talbott). However, Talbott said that Beversluis "had no concern for accuracy" and even that he "had deliberately removed a modal operator" from one of Talbott's statements, and that steps over the line.
One important piece of evidence that makes me very reluctant to charge Beversluis with dishonesty is the fact that, in spite of the fact that it would advance the overall thesis of Beversluis's book that Lewis's apologetics fails miserably, in a review of A. N. Wilson's biography, and later in the revised book, he argued that Lewis did not abandon apologetics after his exchange with Elizabeth Anscombe. No one trying to tear Lewis down dishonestly would have given up on what I have called the Anscombe Legend. That legend is just too juicy for Lewis's opponents to throw away, and the only reason someone like Beversluis would abandon it was because it doesn't fit the facts.
It is very irritating, surely to be misinterpreted by a critic. However, we cannot do better than follow the example of Lewis himself, in his Rejoinder to Dr. Pittenger.
How many times does a man have to say something before he is safe from the accusation of having said exactly the opposite? (I am not for a moment imputing dishonesty to Dr. Pittenger; we all know too well how difficult it is to grasp or retain the substance of a book one finds antipathetic.)"
In any event, Talbott has made some revisions in his essay to meet my criticisms. Those who want to determine how right, or wrong, Talbott is in his criticisms of Beversluis's interpretations should read Talbott's original article, read Beversluis's criticisms, and read Talbott's response. I realize that the relevant portions of Beversluis aren't available online.