What drives liberalism and what drives conservatism?

[E_Smith]

I was thinking today about the difference between a liberal and a conservative. Often people remark that liberals have compassion, while conservatives do not... that conservatives think with their head and liberals their heart. There is that famous Winston Churchill quote, "if you are young and conservative you have no heart. if you are old and liberal you have no head."

I used to accept these notions. Then it occurred to me that this is not the case at all, and in fact almost the opposite is true. The root of liberalism is found in the values of the enlightenment, that the power of reason is much better than the power of faith--and this is what progressives really stand for. So in truth, liberalism is driven by reason and a constant analysis of the facts, while conservatism is driven by ideology. Edit to add: the resultant compassion of liberals is really the result of reason, or the head, NOT the heart!

Now its obvious today that Bush is incredibly ideological as are the neocons. But notwithstanding Bush, do you see ideology as the driving influence of conservatism and reason that of liberalism, or is there an equal mix on both sides of reason/ideology?