The Economics of Sex and Staffing

Why is it that people who hold to being liberal, open-minded and educated can so quickly throw all that away when the subject of sex and babies comes up? How is it that they so quickly confuse correlation with causality?
I'll offer two examples and ask readers to enlighten me. The first involves a chapter from a recent book by economist Steven Landsburg. The second originates from a lecture I heard this last week at a recruiting conference.

http://staffingtechnology.blogspot.com/2007/07/fallacy-detective-is...