A Laughable Attack on Common Descent

I like to keep tabs on some of the more prominent creationist websites, such as the Discovery Institute’s “Evolution News & Views” page and William Dembski’s group blog “Uncommon Descent.” Cornelius Hunter, author of some cdesign proponentsist book or other, has been making regular appearances on both sites lately, cross-posting items from his own blog.

Many of his rantings have fallen into the classic fallacy of argument from incredulity: “I personally can’t imagine how X could be possible (and I’m going to ignore your attempts to explain X), therefore X is impossible.” It’s hardly worth addressing such resolute and deliberate ignorance.

But one post of his, which appeared at the Disco ‘Tute the other week, contained a particularly glaring abuse of logic. He uses a recent study, an investigation into the potential evolutionary origins of laughter, as an excuse to lash out at the evidence backing common descent:

Evolutionists group species by similarities, thinking this reveals patterns of common descent. Then they find another similarity (not surprisingly with the same pattern) and they conclude it must have evolved. After all, it fits the pattern.

Hunter goes on to call common descent “laughable.” But I’m absolutely stymied by his parenthetical note above. If he rejects common descent, why isn’t he surprised to see a new similarity fit the same pattern? I therefore pose this question to Hunter, or anyone who thinks they can suggest an answer. Please, enlighten me.

Why would otherwise completely unrelated traits exhibit common patterns of shared expression between species, unless those traits conform to an overarching pattern of inheritance via common descent?