This paper applies the theory of networks to the problem of how agents should assign weights to other agents in the Lehrer-Wagner model for consensus formation. The Lehrer- Wagner theory of consensus is introduced, and the problem of weight assignment is highlighted as one of the open prob- lems for the theory. The paper argues that the application of the theory of networks to the Lehrer-Wagner model con- stitutes an interesting and fruitful option, among others, for the problem of weight (...) assignment. (shrink)

It is widely believed that bringing parties with differing opinions together to discuss their differences will help both in securing consensus and also in ensuring that this consensus closely approximates the truth. This paper investigates this presumption using two mathematical and computer simulation models. Ultimately, these models show that increased contact can be useful in securing both consensus and truth, but it is not always beneficial in this way. This suggests one should not, without qualification, support policies which increase interpersonal (...) contact if one seeks to improve the epistemic performance of groups. (shrink)

In this paper we shed new light on the Argument from Disagreement by putting it to test in a computer simulation. According to this argument widespread and persistent disagreement on ethical issues indicates that our moral opinions are not influenced by any moral facts, either because no such facts exist or because they are epistemically inaccessible or inefficacious for some other reason. Our simulation shows that if our moral opinions were influenced at least a little bit by moral facts, we (...) would quickly have reached consensus, even if our moral opinions were affected by factors such as false authorities, external political shifts, and random processes. Therefore, since no such consensus has been reached, the simulation gives us increased reason to take seriously the Argument from Disagreement. Our conclusion is however not conclusive; the simulation also indicates what assumptions one has to make in order to reject the Argument from Disagreement. The simulation algorithm we use builds on the work of Hegselmann and Krause (J Artif Soc Social Simul 5(3); 2002, J Artif Soc Social Simul 9(3), 2006). (shrink)

John Mackie's stimulating book is a complete and clear treatise on moral theory. His writings on normative ethics-the moral principles he recommends-offer a fresh approach on a much neglected subject, and the work as a whole is undoubtedly a major contribution to modern philosophy.The author deals first with the status of ethics, arguing that there are not objective values, that morality cannot be discovered but must be made. He examines next the content of ethics, seeing morality as a functional device, (...) basically the same at all times but changing significantly in response to changes in the human condition. He sketches a practical moral system, criticizing but also borrowing from both utilitarian and absolutist views. Thirdly, the frontiers of ethics, areas of contact with psychology, metaphysics, theology, law and politcs, are explored.Throughout, his aim is to discuss a wide range of questions that are both philosophical and practical, working within a distinctive version of subjectivism-an "error" theory of the apparent objectivity of values. John Mackie has drawn on the contributions of such classic thinkers as Plato, Aristotle, Hobbes, Hume, Kant and Sidgwick, and on more recent discussions, to produce a thought-provoking account that will inspire both the general reader and the student of philosophy. (shrink)

Moral Realism is a systematic defence of the idea that there are objective moral standards. Russ Shafer-Landau argues that there are moral principles that are true independently of what anyone, anywhere, happens to think of them. His central thesis, as well as the many novel supporting arguments used to defend it, will spark much controversy among those concerned with the foundations of ethics.

Moral psychology investigates human functioning in moral contexts, and asks how these results may impact debate in ethical theory. This work is necessarily interdisciplinary, drawing on both the empirical resources of the human sciences and the conceptual resources of philosophical ethics. The present article discusses several topics that illustrate this type of inquiry: thought experiments, responsibility, character, egoism v . altruism, and moral disagreement.

This paper highlights some connections between work on truth approximation and work in social epistemology, in particular work on peer disagreement. In some of the literature on truth approximation, questions have been addressed concerning the efficiency of research strategies for approximating the truth. So far, social aspects of research strategies have not received any attention in this context. Recent findings in the field of opinion dynamics suggest that this is a mistake. How scientists exchange and take into account information about (...) each others’ beliefs may greatly influence the accuracy and speed with which the scientific community as a whole approximates the truth. On the other hand, social epistemologists concerned with peer disagreement have so far neglected the question of how practices of responding to disagreements with peers fare with respect to the goal of approximating the truth. Again, work on opinion dynamics shows that this may be a mistake, and that how we ought to respond to disagreements with our peers may depend on the specific purposes of our investigations. (shrink)

In a seminal book, Alvin I. Goldman outlines a theory for how to evaluate social practices with respect to their , i.e., their tendency to promote the acquisition of true beliefs (and impede the acquisition of false beliefs) in society. In the same work, Goldman raises a number of serious worries for his account. Two of them concern the possibility of determining the veritistic value of a practice in a concrete case because (1) we often don't know what beliefs are (...) actually true, and (2) even if we did, the task of determining the veritistic value would be computationally extremely difficult. Neither problem is specific to Goldman's theory and both can be expected to arise for just about any account of veritistic value. It is argued here that the first problem does not pose a serious threat to large classes of interesting practices. The bulk of the paper is devoted to the computational problem, which, it is submitted, can be addressed in promising terms by means of computer simulation. In an attempt to add vividness to this proposal, an up-and-running simulation environment (Laputa) is presented and put to some preliminary tests. (shrink)

This paper applies the theory of networks to the problem of how agents should assign weights to other agents in the Lehrer-Wagner model for consensus formation. The Lehrer- Wagner theory of consensus is introduced, and the problem of weight assignment is highlighted as one of the open prob- lems for the theory. The paper argues that the application of the theory of networks to the Lehrer-Wagner model con- stitutes an interesting and fruitful option, among others, for the problem of weight (...) assignment. (shrink)

In a seminal book, Alvin I. Goldman outlines a theory for how to evaluate social practices with respect to their “veritistic value”, i.e., their tendency to promote the acquisition of true beliefs in society. In the same work, Goldman raises a number of serious worries for his account. Two of them concern the possibility of determining the veritistic value of a practice in a concrete case because we often don't know what beliefs are actually true, and even if we did, (...) the task of determining the veritistic value would be computationally extremely difficult. Neither problem is specific to Goldman's theory and both can be expected to arise for just about any account of veritistic value. It is argued here that the first problem does not pose a serious threat to large classes of interesting practices. The bulk of the paper is devoted to the computational problem, which, it is submitted, can be addressed in promising terms by means of computer simulation. In an attempt to add vividness to this proposal, an up-and-running simulation environment is presented and put to some preliminary tests. (shrink)

The purpose of this paper is to present a formal model of social net- works suitable for studying questions in social epistemology. We show how to use this model, in conjunction with a computer program for simulating groups of inquirers, to draw conclusions about the epistemological prop- erties of different social practices. This furnishes us with the beginnings of a systematic research program in social epistemology, from which to approach problems pertaining to epistemic value, optimal organization, and the dynamics of (...) multi-agent inquiry. (shrink)

Epistemologists can be divided into two camps: those who think that nothing short of certainty or (subjective) probability 1 can warrant assertion and those who disagree with this claim. This paper addressed this issue by inquiring into the problem of setting the probability threshold required for assertion in such a way that that the social epistemic good is maximized, where the latter is taken to be the veritistic value in the sense of Goldman (Knowledge in a social world, 1999). We (...) provide a Bayesian model of a test case involving a community of inquirers in a social network engaged in group deliberation regarding the truth or falsity of a proposition $p.$ p . Results obtained by means of computer simulation indicate that the certainty rule is optimal in the limit of inquiry and communication but that a lower threshold is preferable in less idealized cases. (shrink)