This is widely discussed. Democrats have more undervotes than republicans, because Republicans have a higher overall educational level and thus income. but when 'advanced degrees' are considered separately, more holders of master's doctorates and professional degrees are democrats. That map correlates somewhat with democrat and republican plurality states in 2000. Not surprising. It is no doubt due to the fact that most phd physicists, chemists, biologists get 100% of their income, either directly or indirectly from the united states government from taxpayers. It is not surprising that most lawyers are Democrats and most physicians are Republicans, by similar a public vs. private funding analysis, or, in the case of ambulance chasers such as Senator Edwards, the willingness of the Democrats to pass laws favorable to a high standard of living for attorneys, many of whom are politicians.
There is another factor in considering the voting behavior of those with advanced degrees. I'll address academic PhDs, based on 25 years of interaction.
As a group, I find academics far more likely to vote against their economic self-interest. In many cases, personal philosophy trumps personal interest. For instance, the fact that the local Congressman is a great supporter of scientific research doesn't count if he's wrong on social issues. It ironic when the research funding is of immediate benefit, but the social issues have little or no impact at the personal level.
