JA has broken men down into two categories.

The first is those who subscribe to the credo of "Now don't you worry your pretty little head about it, I'll take care of the thinking for both of us."

The second group is more "reasonable" and "well informed", but they still find an ignorant woman more attractive than one who is herself reasonable and well informed. Even in this group, apparently the goal is not to throw off one's ignorance eventually, but to remain ignorant in various ways so that the man will have more opportunities to show how reasonable and well informed he is.

At least, that's how I read the passage: guys want a woman to be dependant on them for the mental heavy lifting to one degree (imbecility) or another (ignorance), and a smart woman who wants to attract that guy would do well to hide her smarts. It's also a masterfully funny bit of writing! See how turgid and pedantic it sounds when I try to put it in my own words?

Thanks for bringing this up, Karen G.