Show-Me the Argument

Conservatism is often defined as follows:

(C) If S believes that p, then, in the absence of defeaters, S thereby has at least some degree of justification for believing that p.

I will now give a rough characterization of the distinction between propositional and doxastic justification for p. For S to have propositional justification for her belief that p is for her to have reasons for her belief that p. This does not imply that S bases her belief on those reasons; S might believe that p on a whim or she might not even believe p at all. However, if S has propositional justification for p and S bases her belief that p on her propositional justification, then S has doxastic justification for p. These considerations show that propositional justification for a belief alone does not make a belief have any positive epistemic status. Sally might have great reasons for believing that there has been an increase in global warming (say, the testimony of reliable scientists she knows), but if her belief is based solely on the results of her ouija ball, then her belief has little positive epistemic status. However, if she bases her belief on the testimony of those scientists, then the belief will have positive epistemic status; it will be doxastically justified.

Note that in the previous paragraph, the condition that one base her belief on her propositional justification is only a sufficient condition for doxastic justification; there are some who think that one can have doxastic justification for a belief without any propositional justification at all. An externalist, for example, might think that a belief can be doxastically justified if it is formed in the appropriate way by an external process, even in the absence of any propositional justification. Internalists will tend to disagree; a belief is doxastically justified only if it is propositionally justiifed. We do not need to resolve this dispute here; everyone will agree that, in a large number of cases, a belief is doxastically justified only if it is justified by one’s reasons, i.e., by one’s propositional justification. This shows that propositional justification should be deemed important by both internalists and externalists alike.

Given these points, (C) must be a principle of doxastic justification and not propositional justification. For suppose (C) is a principle of propositional justification. Then the propositional justification for a belief is the belief itself. But note that such a belief will not be able to be doxastically justified on the basis of this propositional justification. For it is impossible to form a belief on the basis of itself. Consider the widely held view that a belief is based on a some bit of propositional justification j only if j is, in some appropriate sense, the cause of the belief. But self-causation in epistemology is just as bad as self-causation in the cosmological argument; a belief cannot cause itself to exist. So even if (C) states a correct principle of propositional justification, it does not state how a belief could have a status any better than Sally’s belief in global warming on the basis of her ouija ball. Surely the proponents of conservatism intend for (C) to state more than that. They must intend it, therefore, as a theory of doxastic justification. It also follows that such theorists will join externalists in thinking that a belief can be doxastically justified without propositional justification.

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