A brief note on how to define conservatism in light of the last post’s discussion of the important role epistemology plays in forming political ideologies. How can we express conservatism’s uniqueness in terms of its epistemological distinctiveness?
I suggest we think of conservatism as comprised of two compatible but qualitatively unique traits: 1) an absolute commitment to certain metaphysical axioms and values that does not yield to subsequent empirical, consequentialist calculations; and 2) a conditional commitment to a body of economic, regulative and policy ideals motivated by those axioms and values that are, at least in theory, prone to empirical falsification. It’s the former category of traits that distinguishes true conservatism, as the portion of empirically-falsifiable ideals are susceptible to constant revision and refutation in response to emerging data, and may be espoused by other ideologies inimical to conservatism’s metaphysical axioms. E.g., conservatives generally promote low taxation as a hallmark of their political sensibility. But if low taxation were empirically proven to be an ineffective means of generating wealth and prosperity, conservatives might plausibly reject it without violating their core beliefs. And low taxation is hardly unique to conservatism; other political ideologies advocate it. Low taxation is on this view a contingent feature of conservatism and not among its indispensable tenets. While low taxation appears consistent with the metaphysical commitments upon which true conservatism rests, our ability to extrapolate certain practical policies from those general principles is imperfect and therefore subject to correction.
Conservatism, on this definition, is contrasted from its rivals by its employment of a different sort of epistemological justification. [Most] Progressives are wholly reliant upon empirical means of justifying their policy prescriptions, for they not only deny that other methods of confirmation are suitable for determining the fitness of competing political virtues, but they dispute the existence of a transcendent order that might necessitate the use of other such methods. Quantitative/pragmatic analysis is the only sort of criterion available to the progressive. Conservatives on the other hand are willing to appeal to quantitative data to bolster support for their contingent policy recommendations, but unlike progressives will also resort to other epistemological registers to validate their absolute adherence to what they view as timeless truths. These other registers admit of a priori reasoning and special revelation, both of which are the true sources of conservative axioms.
An interesting upshot of this definition of conservatism is that it renders those who adhere to the merely contingent set of conservative ideals but jettison its absolute axioms nominal conservatives. Such persons claim only those aspects of conservatism shared, at least theoretically, by other ideologies and do not endorse the irreducible essence of the political philosophy. This definition therefore establishes as a necessary condition of genuine conservatism a commitment to at least a priori reasoning and perhaps also religious revelation, and somewhat downplays the significance of seminal conservative figures such as Burke who, though a proponent of conservative ideals such as prudent restraint and fair taxation, does not necessarily express an absolute devotion to a body of a priori knowledge or religious truth.
Granting the usefulness and accuracy of such a description of conservatism, who left among the political elite may be called genuinely conservative?
 By subsequent, I mean any empirical evidence encountered after a conclusion has been reached on the validity of the governing metaphysical commitments anchoring conservatism. I’m not suggesting that the metaphysical commitments themselves are immune from empirical falsification. Only that, short of supplying evidence contradicting those metaphysical commitments, the influence of subsequent empirical data will be limited to the contingent aspects of conservative policy.