When I use the term "conservative" below, I mean the term as applicable until Buckley, Thatcher, Reagan and the neocons redefined it. "Conservativism" today supports individualism (hence their sympathy for Ayn Rand) and belief in an ideal economic-political system that could be applied to the whole world, making it ontologically distinct from conservativism which was partially and importantly defined by rejection of these things.
Conservativism starts as a modernist (those who think Joseph de Maistre is a medievalist, don't know what they're talking about) reaction to the French Revolution. However I will note that it comes from two very distinct angles: one angle is Anglo-American conservativism, exemplified by Edmund Burke, John Adams and Russell Kirk. Here conservativism is a Whig (for what that was in the 18th Century, which was much more heterogenous than in the 19th) school of thought which embraced both the Glorious Revolution and the American Revolution. Hence its critique of the French Revolution is in contrast to those. From an Anglo conservative perspective, these revolutions were required to protect the law. The French Revolution, by contrast, was not about upholding the law, it was about subverting it by anarchy, extrajudicial murder and mob lynchings. Consequently Anglo conservativism places enormous value on rule of law, of following the law as (for lack of a better term) dogmatically as possible. Judges ought to interpret the law by intent, the executive cannot go beyond her constitutional authority, etc. Law is only to be changed by the means the law prescribes for her change.
In contrast, Continental conservativism critiqued the French Revolution more on the basis of defending the deposed government. So instead of defending written law, Continental conservativism is more concerned with unwritten law and justifying regime. Whereas the American conservative might say Lincoln's suspension of habaes corpus is valid because the Constituion permits it in time of rebellion, de Maistre is overtly concerned with when the state can suspend it *without* explicit provision in written law. For de Maistre and Carl Schmitt, the central legal question is not what the law permits, but when the state can and ought to act outside written law.
This leads to some startling differences. Solzhenitsyn, for instance, said America is too "legalistic", which might shock an American conservative, seeing as Solzhenitsyn's writings (to us) suggest the USSR's major problem is the state being completely beyond the law. Solzhenitsyn would say no, the problem is that the state cared about ideology rather than God.
The last conservative (in the older sense) POTUS was Richard Nixon. An Anglo school conservative is likely to strongly approve of much of his policy as a president, while seeing his criminal behavior as dangerous and subversive, whereas a Continental school conservative is more likely to sympathize with G. Gordon Liddy's defense of it.
