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The impossibility results of Bovens and Hartmann (2003) and Olsson (2005) call into question the strength of the connection between coherence and truth. As part of the inquiry into this alleged link, I define a notion of degree of truth-conduciveness, relevant for measuring the usefulness of coherence measures as rules-of-thumb for assigning probabilities in situations of partial knowledge. I use the concept to compare the viability of some of the measures of coherence that have been suggested so far under different circumstances. It turns out that all of these, including the prior, are just about equally good in cases of very little knowledge. Nevertheless, there are differences in when they are applicable, and they also depart more from each other when more knowledge is added. CiteULike    Connotea    Del.icio.us    What's this?

Cognitive scientific realism as presented in my previous paper is amended to include a new and strong epistemic indicator for truth of scietific theories: theory coherence and by implication level coherence. Interestingly, this coherence exists despite the incommensurability of the ontology of different levels. Combined with empirical adequacy, theory coherence provides convincing arguments for the confutation of antirealist views. Specifically, fundamentalism, underdetermination, and instrumentalism are considered.

In this paper I am primarily interested in establishing that a coherence theory of truth is conceptually incoherent. Although my primary concern is with the coherence theory of truth, I shall point out that the problem I raise has a striking parallel in a now well-known objection to coherence theories of justification (an objection that, ironically, was brought to the fore by a proponent of a coherence theory of justification, Laurence Bonjour).

Quine argues, in “On the Nature of Moral Values” that a coherence theory of truth is the “lot of ethics”. In this paper, I do a bit of work from within Quinean theory. Specifically, I explore precisely what a coherence theory of truth in ethics might look like and what it might imply for the study of normative value theory generally. The first section of the paper is dedicated to the exposition of a formally correct coherence truth predicate, the possibility of which has been the subject of some skepticism. In the final two sections of the paper, I claim that a coherence theory in ethics does not reduce the practice of moral inquiry to absurdity, in practice as well as in principle.

There is an emerging consensus in the literature on probabilistic coherence that such coherence cannot be truth conducive unless the information sources providing the cohering information are individually credible and collectively independent. Furthermore, coherence can at best be truth conducive in a ceteris paribus sense. Bovens and Hartmann have argued that there cannot be any measure of coherence that is truth conducive even in this very weak sense. In this paper, I give an alternative impossibility proof. I provide a relatively detailed comparison of the two results, which turn out to be logically unrelated, and argue that my result answers a question raised by Bovens and Hartmann’s study. Finally, I discuss the epistemological ramifications of these findings and try to make plausible that a shift to an explanatory framework such as Thagard’s is unlikely to turn the impossibility into a possibility.

Erik Olsson’s Against Coherence: Truth, Probability, and Justification is an important contribution to the growing literature on Bayesian coherentism. The book applies the formal theory of probability to issues of coherence in two contexts. One is the philosophical debate over radical skepticism, and the other is common sense and scientific reasoning. As the title of the book suggests, Olsson’s view about coherence is negative on both accounts. With regard to radical skepticism, Olsson states that “the connection between coherence and truth is […] too weak to allow coherence to play the role it is supposed to play in a convincing response to radical scepticism.” (viii) Olsson also states, with regard to common sense and scientific reasoning, that “there is no way to specify an informative notion of coherence that would allow us to draw even the minimal conclusion that more coherence means a higher likelihood of truth other things being equal”. (viii) I want to begin with the second point, which is the more surprising of the two.

The coherence of the whole truth is a presupposition of any holistic coherence theory of justification that postulates a positive connection between justification and truth, for unless the whole truth is itself systemically coherent there is no reason to look for systemic coherence when deciding whether one is justified in accepting a given body of beliefs as true. This paper develops a formal model of holistic evidential coherence and uses this model to formalize and defend the claim that the whole truth must be coherent in an evidential sense.

It is tempting to think that, if a person's beliefs are coherent, they are also likely to be true. This truth conduciveness claim is the cornerstone of the popular coherence theory of knowledge and justification. Erik Olsson's new book is the most extensive and detailed study of coherence and probable truth to date. Setting new standards of precision and clarity, Olsson argues that the value of coherence has been widely overestimated. Provocative and readable, Against Coherence will make stimulating reading for epistemologists and anyone with a serious interest in truth.

There is an objection to coherence theories of knowledge to the effect that coherence is not connected with truth, so that when coherence leads to truth this is just a matter of luck. Coherence theories embrace falliblism, to be sure, but that does not sustain the objection. Coherence is connected with truth by principles of justified acceptance that explain the connection between coherence and truth. Coherence is connected with truth by explanatory principle, not just luck.

What is the relation between coherence and truth? This paper rejects numerous answers to this question, including the following: truth is coherence; coherence is irrelevant to truth; coherence always leads to truth; coherence leads to probability, which leads to truth. I will argue that coherence of the right kind leads to at least approximate truth. The right kind is explanatory coherence, where explanation consists in describing mechanisms. We can judge that a scientific theory is progressively approximating the truth if it is increasing its explanatory coherence in two key respects: broadening by explaining more phenomena and deepening by investigating layers of mechanisms. I sketch an explanation of why deepening is a good epistemic strategy and discuss the prospect of deepening knowledge in the social sciences and everyday life.