Online research in philosophy

Bayesian Coherence Theory of Justification or, for short, Bayesian Coherentism, is characterized by two theses, viz. (i) that our degree of confidence in the content of a set of propositions is positively affected by the coherence of the set, and (ii) that coherence can be characterized in probabilistic terms. There has been a longstanding question of how to construct a measure of coherence. We will show that Bayesian Coherentism cannot rest on a single measure of coherence, but requires a vector whose components exhaustively characterize the coherence properties of the set. Our degree of confidence in the content of the information set is a function of the reliability of the sources and the components of the coherence vector. The components of this coherence vector are weakly but not strongly separable, which blocks the construction of a single coherence measure.

This paper sets out to demonstrate that a contrast can be drawn between coherentism as an account of the structure of justification, and coherentism as a method of inquiry. Whereas the former position aims to offer an answer to the ‘regress of justification’ problem, the latter position claims that coherence plays a vital and indispensable role as a criterion of truth, given the fallibility of cognitive methods such as perception and memory. It is argued that ‘early’ coherentists like Bradley and Blanshard were coherentists of the latter kind, and that this sort of coherentism is not open to certain sorts of standard objection that can be raised against justificatory coherentism.

Recent results in probability theory have cast doubt on coherentism, purportedly showing (a) that coherence among a set of beliefs cannot raise their probability unless individual beliefs have some independent credibility, and (b) that no possible measure of coherence makes coherence generally probability-enhancing. I argue that coherentists can reject assumptions on which these theorems depend, and I derive a general condition under which the concurrence of two information sources lacking individual credibility can raise the probability of what they report.

One of the most influential arguments for the coherence theory of empirical justification is BonJours a priori argument from the internalist regress. According to this argument, foundationalism cannot solve the problem of the internalist regress since internalism is incompatible with basic beliefs. Hence, coherentism seems to be the only option. In my article I contend that this argument is doomed to failure. It is either too strong or too weak. Too strong, since even coherentism cannot stop the internalist regress in any legitimate way. In order to demonstrate this claim I will discuss various coherentist strategies. Too weak, since, were coherentism able to stop the regress, the argument against foundationalism would collapse.

In this paper I prove that holistic coherentism is logically equivalent to the conjunction of symmetry and quasi-transitivity of epistemic support and a condition on justified beliefs. On the way I defend Tom Stoneham from a criticism made by Darrell Rowbottom and prove a premiss of Stoneham’s argument to be an entailment of coherentism.

Some members of the Vienna Circle argued for a coherence theory of truth. Their coherentism is immune to standard objections. Most versions of coherentism are unable to show why a sentence cannot be true even though it fails to cohere with a system of beliefs. That is, it seems that truth may transcend what we can be warranted in believing. If so, truth cannot consist in coherence with a system of beliefs. The Vienna Circle's coherentists held, first, that sentences are warranted by coherence with a system of beliefs. Next they drew upon their verification theory of meaning, a consequence of which is that truth cannot transcend what can be warranted. The coherence theory of knowledge and verificationism together entail that truth cannot transcend what can be warranted by coherence with a system of beliefs. The Vienna Circle's argument for coherentism is strong and anticipates contemporary anti-realism.

Among many reasons for which contemporary philosophers take coherentism in epistemology seriously, the most important is probably the perceived inadequacy of alternative accounts, most notably misgivings about foundationalism. But coherentism also receives straightforward support from cases in which beliefs are apparently justified by their coherence. From the perspective of those against coherentism, this means that an explanation is needed as to why in these cases coherence apparently justifies beliefs. Curiously, this task has not been carried out in a serious way in the anti-coherentist literature although there is no scarcity of objections to coherentism. The traditional charge has been that justification by coherence is circular. More recently the isolation problem allegedly reveals that coherentism justifies beliefs that should not be justified. Questions have also been raised with respect to the basing relation and feasibility.1 However, these objections do not explain why some beliefs appear to be justified by their coherence. This paper fills this gap in the anti-coherentist literature by offering a noncoherentist account of justification by coherence. The paper proceeds as follows. Section I delineates the framework of discussion and develops some conceptual tools needed in later analyses. Section II argues that there are genuine cases of an increase in existing empirical justification by coherence, but that it does not require coherence to generate additional justification—coherence serves as a channel of justification among beliefs, which is no more problematic than channeling of justification from basic to derived beliefs in foundationalism. Section III makes a stronger case for justification by coherence, where each of the coherent beliefs has no independent empirical justification; but Section IV argues that even in these cases coherence need not generate justification—coherence licenses the channeling of justification from outside sources..

A general theory of coherence is proposed, in which systemic and relational coherence are shown to be interdefinable. When this theory is applied to sets of sentences, it turns out that logical closure obscures the distinctions that are needed for a meaningful analysis of coherence. It is concluded that references to “all beliefs” in coherentist phrases such as “all beliefs support each other” have to be modified so that merely derived beliefs are excluded. Therefore, in order to avoid absurd conclusions, coherentists have to accept a weak version of epistemic priority, that sorts out merely derived beliefs. Furthermore, it is shown that in belief revision theory, coherence cannot be adequately represented by logical closure, but has to be represented separately.

In a recent article, Peter Gärdenfors (1992) has suggested that the AGM (Alchourrón, Gärdenfors, and Makinson) theory of belief revision can be given an epistemic basis by interpreting the revision postulates of that theory in terms of a version of the coherence theory of justification. To accomplish this goal Gärdenfors suggests that the AGM revision postulates concerning the conservative nature of belief revision can be interpreted in terms of a concept of epistemic entrenchment and that there are good empirical reasons to adopt this view as opposed to some form of foundationalist account of the justification of our beliefs. In this paper I argue that Gärdenfors’ attempt to underwrite the AGM theory of belief revision by appealing to a form of coherentism is seriously inadequate for several reasons.

Coherentism is a theory of epistemic justification. It implies that for a belief to be justified it must belong to a coherent system of beliefs. For a system of beliefs to be coherent, the beliefs that make up that system must “cohere” with one another. Typically, this coherence is taken to involve three components: logical consistency, explanatory relations, and various inductive (non-explanatory) relations. Rival versions of coherentism spell out these relations in different ways. They also differ on the exact role of coherence in justifying beliefs: in some versions, coherence is necessary and sufficient for justification, but in others it is only necessary.