From The Art of Manliness, rules on the proper wearing of socks.
This is a rule that many people are confused about. I’ve heard numerous arguments about whether you should match socks with shoes or socks with pants. You should always match socks with pants because when you sit down and your socks are exposed, you want a solid line of color from your pants to your shoes. Socks that don’t match your pant color create a jarring break in your outfit. So black socks go with black pants and brown socks go with brown pants. Absolutely and under no condition should you ever wear white socks with dark pants unless you want to look like Steve Erkle or 1980’s Michael Jackson.