Online research in philosophy

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.

Coherentists on epistemic justification claim that all justification is inferential, and that beliefs, when justified, get their justification together (not in isolation) as members of a coherent belief system. Some recent work in formal epistemology shows that “individual credibility” is needed for “witness agreement” to increase the probability of truth and generate a high probability of truth. It can seem that, from this result in formal epistemology, it follows that coherentist justification is not truth-conducive, that it is not the case that, under the requisite conditions, coherentist justification increases the probability of truth and generates a high probability of truth. I argue that this does not follow.

If coherence is to have justificatory status, as some analytical philosophers think it has, it must be truth-conducive, if perhaps only under certain specific conditions. This paper is a critical discussion of some recent arguments that seek to show that under no reasonable conditions can coherence be truth-conducive. More specifically, it considers Bovens and Hartmann’s and Olsson’s “impossibility results,” which attempt to show that coherence cannot possibly be a truth-conducive property. We point to various ways in which the advocates of a coherence theory of justification may attempt to divert the threat of these results.

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.

This paper argues that formal models of coherence are useful for constructing a legal epistemology. Two main formal approaches to coherence are examined: coherence-based models of belief revision and the theory of coherence as constraint satisfaction. It is shown that these approaches shed light on central aspects of a coherentist legal epistemology, such as the concept of coherence, the dynamics of coherentist justification in law, and the mechanisms whereby coherence may be built in the course of legal decision-making.

Bovens and Hartmann (Bayesian Epistemology, Oxford: Oxford University Press, 2003) propose to analyze coherence as a confidence-boosting property. On the basis of this idea, they construct a new probabilistic theory of coherence. In this paper, I will attempt to show that the resulting measure of coherence clashes with some of the intuitions that motivate it. Also, I will try to show that this clash is not due to the view on coherence as a confidence-boosting property or to the general features of the model that Bovens and Hartmann use to analyze coherence. It will turn out that there is at least one other measure that is similarly based on the concept of a confidence-boosting property, but does not have the same counterintuitive results.

Bovens and Hartmann (Bayesian Epistemology, Oxford: Oxford University Press, 2003) propose to analyze coherence as a confidence-boosting property. On the basis of this idea, they construct a new probabilistic theory of coherence. In this paper, I will attempt to show that the resulting measure of coherence clashes with some of the intuitions that motivate it. Also, I will try to show that this clash is not due to the view on coherence as a confidence-boosting property or to the general features of the model that Bovens and Hartmann use to analyze coherence. It will turn out that there is at least one other measure that is similarly based on the concept of a confidence-boosting property, but does not have the same counterintuitive results.

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..

This is a review of Erik J. Olsson, AGAINST COHERENCE: TRUTH, PROBABILITY AND JUSTIFICATION (Oxford: Clarendon Press, 2005).

A measure of coherence is said to be truth conducive if and only if a higher degree of coherence (as measured) results in a higher likelihood of truth. Recent impossibility results strongly indicate that there are no (non-trivial) probabilistic coherence measures that are truth conducive. Indeed, this holds even if truth conduciveness is understood in a weak ceteris paribus sense (Bovens & Hartmann, 2003, Bayesian epistemology. New York, Oxford: Oxford University Press; Olsson, 2005, Against coherence: Truth probability and justification. Oxford: Oxford University Press). This raises the problem of how coherence could nonetheless be an epistemically important property. Our proposal is that coherence may be linked in a certain way to reliability. We define a measure of coherence to be reliability conducive if and only if a higher degree of coherence (as measured) results in a higher probability that the information sources are reliable. Restricting ourselves to the most basic case, we investigate which coherence measures in the literature are reliability conducive. It turns out that, while a number of measures fail to be reliability conducive, except possibly in a trivial and uninteresting sense, Shogenji’s measure and several measures generated by Douven and Meijs’s recipe are notable exceptions to this rule.