From the wikipedia entry on Freethought: Freethought or free thought is a philosophical viewpoint that holds opinions should be formed on the basis of logic, reason, and empiricism, rather than authority, tradition, or other dogmas. The cognitive application of freethought is known as "freethinking", and practitioners of freethought are known as "freethinkers".
Interesting definition. Logic, reason and empiricism? Then it turns out everyone from Thomas Aquinas to William Lane Craig was a freethinker after all. 'Ah,' may come the reply. 'But at least on some subjects those men submitted to authority!' Alright... but if authority is verboten, then it looks like almost none of the people who are commonly held up as free thinkers really are, since every one of them bows to various authorities - particularly 'scientific consensus.' If someone argues that scientists qualify as acceptable authorities because they presumably have knowledge to back up their statements, then we're right back to accepting Aquinas and company as free thinkers too - since God certainly has the knowledge to back up HIS statements. Better yet, at least in the case of God there are metaphysical arguments for His knowledge, His omniscience. For any particular scientist or group of scientists? It gets a lot trickier.
I think the very idea of 'free thought' originated in a time and place that is so unlike our own that the concept, as it was originally presented, really died a long time ago - and it wasn't a very good idea even in its original form. Part of the problem seems to be the tendency to think of favored and individuals in a 'we' sense instead of a 'they' sense. How many times do you run into people who say "We used to think geocentrism is true, but now we know that heliocentrism is true!", only to find out that "We know" means "This is what I heard that scientists say", and if you ask them to explain how - do this when they're not near a computer or aren't allowed to check the internet - they come up short? 'We know', meaning 'Someone out there knows, I hear'. 'We discovered geocentrism is false' meaning 'Didn't someone do, like, an experiment?'
If freethought allows other people to do our thinking for us, then the entire edifice collapses and everyone is a free thinker. If other people are not allowed to do our thinking for us, then the price is a level of agnosticism that modern free thinkers would find downright worrisome. The only route left is to head off into the fog and argue that it's all very complicated and therefore necessary to consider that some levels of dogma or authority may well be acceptable after all, at which point Thomas Aquinas the Freethinker is, at the very least, a live option - and Richard Dawkins, the anti-skeptic, is as well.