1) She is the sort of person who comes to VERY considered conclusions and opinions after lots of thought and work. This is, after all, what academic research is.

2) Intelligence and deep contemplation are central to an academic’s self identity. Arguing an issue, and losing because of a stupid arguement, would be a more central blow to self-identity than ducking the issue. IOW, ’tis better to remain silent, and be thought a fool, than to speak, and prove it.

3) Academics are, heavily, introverts, and also tend toward visual forms of learning. (I.e. learn by read or write, not be speak or hear.)

Writing allows folks to think through their opinions before posting, to craft and edit arguments. Spoken arguments on issues that are not central to one’s research would be like writing a first draft in a different subfield at three in the morning and sending it unedited for review. The result most likely would be rather mortifying by light of day. (Not that people don’t blog like that, but “shy” academics don’t.) So, duck a conversation on a topic, but not an editorial or blog post.

I don’t see being an ‘intellectual’ as being predicated on being a wit. (That is, being predicated on an ability to reel off an opinion, process the return, and give intelligent and strong arguments in ‘real time’ on issues the intellectual knows, but hasn’t reviewed beforehand.)

This is an astute observation. To give an example, consider Noam Chomsky, a brilliant man in his field of expertise (linguistics) who tries to trade on that reputation to make absurd left-wing political pronouncements.

It should not surprise us that the vast majority of people, even academics, come to conclusions on the “big issues” for reasons having nothing to with a careful analysis of the facts and evidence. Indeed, most of the time, we first make emotional commitments as a function of our ingroup loyalties, and then go looking for “reasons” to justify those commitments.

At some level, academics (other than Chomsky) understand this distinction, and they wisely do what you describe: separate their professional opinions from their personal ones.

I’d hope that those who strive for correctness in all areas are better at it professionally as well as in other aspects of life, but I don’t actually have much evidence for that. The truly successful seem batshit crazy on some topics.