In my blog post of February 22, I wrote a line stating that Vice President Joe Biden’s occasionally antic behavior might be explained by a blow to his head at some time in the past from which he had not fully recovered. Shortly after the post appeared, we received an outraged communication from the White House informing Field & Stream that then-Senator Biden, in 1988, had undergone surgery to repair an aneurism in his brain, and demanding retraction of the line.

The retraction was refused, but I would nonetheless like to apologize to Vice President Biden. I was completely unaware of his medical history, and had I known about this episode I would not have joked about the condition. The line I used was inspired by a fragment I dimly recalled from Mark Twain about a mule that had been struck hard in the head and was trying to come to terms with its surroundings.

I’ve requested, through the magazine, that the Obama Administration send me complete medical histories of all its personnel who have anything to do with firearms legislation and about whom I might write so that incidents of this sort can be avoided in the future.