Conservatism =
1. resistance to change
2. reverence for tradition and distrust of human reason
3. rejection of use of government to improve the human condition. Ambivalence regarding government activity for other purposes
4. preference for individual freedom but willingness to limit freedom to maintian traditional values
5. antiegalitarianism=distrust of human nature
Liberals =
1. tendency to favor change that improves the human condition
2. faith in human reason
3. willingnes to use government to improve the human condition
4. preference for individual freedom but ambivalience about economic freedom
5. greater optimism about human nature than conservatives.
[Contemporary Political Ideologies: A Comparative Analysis 13th ed. Lyman Sargent 2006 ISBN.0-534-60241-x]
With this being said, you can see that Liberals prefer to make changes that they see will make things better for all Americans while creating greater freedom for all people rather than just the wealthy.
Conservatives oppose this and yes, should act as a buffer to slow any change to prevent hasty change that may cause problems that cannot be reversed.
But in modern politics, it hasn't become about considering the consequences of change, it has become about opposing anthing a liberal says, and denouncing it as unreasonable. This is actualy a neoconservative believe and what neocons have changed conservatives into.
Wit that being said, the modern conservative movement, with exception of libertarians and paleocons(which are denounce as libertines by traditional cons and the religious right), have become a set of self-conflicting ideologies in order to paint liberals s big government fascists or socialists, while trying to maintain their protradtional moral value beliefs.
example : conservative claim to be for less taxes and less government, but want abortion ban, and stronger penalties for drug users, meanwhile they claim liberals, who want to allow people to make their own decisions on abortion and their own decisions regarding if their child is exposed to religion in schools, want big government.
Abortion ban = more enforcement cost = more taxes
that sounds like promoting big government to me, but conseravtives claim they don't promote big government.
the very hallmark of a conservative is the will to maintain law and order. How do you maintain law and order with a smaller government?
The hallmark of a liberal is the view that individual freedom(within reason) trumps all other concerns in society.