It's not entirely useless to investigate people's backgrounds as a way of understanding their thinking. Mr D'Souza has surely been shaped by the milieu he grew up in and the political ideology that structures it, and Barack Obama was clearly shaped by the experience of growing up partly abroad, with a mixed-race identity that had links to middle-class white America, to black America, and to Africa. I've certainly been shaped by growing up Jewish on the East Coast, Sarah Palin was shaped by growing up Christian in Idaho, and so forth. But I think we do better when we criticise people's ideas and programmes on their own terms, rather than seeking out mysterious causes in their childhoods. There's no need to search for abstruse reasons why an extreme movement conservative like Dinesh D'Souza might oppose raising taxes on the rich or defend privilege in access to education. And it's not surprising that a centrist liberal like Barack Obama thinks people earning more than $250,000 per year ought to be paying more taxes. In fact, that conviction is shared by a majority of the American electorate. If Mr D'Souza finds it bizarre, it's not Mr Obama who's out of touch with America.
We need to do both. I disagree that we should ignore psychological motivation in politics because we need an explanation for irrational acts. Facts and reason are usually ignored during decision-making. We have to understand and explain why so we can address irrational behavior.