Marc Andree Weber

Moral evidentialism is the view that one ought morally to believe only what is suggested by the evidence at one's disposal. As announced in the title, an argument for (a slightly restricted version of) this view is presented. The argument crucially relies on two specific links between belief and assertion, namely that one should not believe what one must not assert, and that one must not assert what is not suggested by the evidence at one's disposal. In both cases, the normativity involved is moral. The links are established, and it is shown how to deal with seemingly apparent counterexamples.

People who, by intention or negligence, deceive themselves put other people at risk of being misinformed. The paper argues that this kind of misinforming other people is to be avoided for largely the same reasons for which lying is to be avoided – regardless of what exactly these reasons are. This makes the ethical evaluation of self-deception in part dependent on the ethical evaluation of lying. In order to bring out this result as clearly as possible, detailed characterisations of the concepts of attempted deception, lying, and self-deception are given.

Recently, epistemologists have been much concerned with the question of whether or not we have to revise our beliefs if there are people whose epistemic position is as good as ours and who disagree with us. The results of such considerations, whatever they are, are sometimes said to be restricted to domains in which, unlike in politics or law, the relevant agents are not under any pressure to act in accordance with their beliefs, have no deeply held ideological beliefs, or have no beliefs that stem from their particular aims or desires. In response to this, and with regard to the paradigmatic cases of politics and law, this article argues that there are no genuine political or legal disagreements: what we call a political or legal disagreement is either no disagreement at all but a mere clash of interest, or it is a an empirical, moral, or practical disagreement that is not genuinely political or legal. To the latter, epistemological insights apply; to the former, they do not.

Many of our ideological, political, moral, religious, aesthetic, scientific beliefs, as well as those concerning everyday life, are controversial; other people do not share them. As a rule, that does not bother us much: we tend to retain our contestable beliefs even if we ascribe no less skill and well-informedness to those who represent other points of view than to ourselves. But is that really reasonable? Shouldn't we often admit that we might be as wrong as others? And if we do, shouldn't this consequently lead us to give up many of our beliefs in favor of agnostic attitudes? Marc Andree Weber argues that in the face of disagreement with equally competent and well-informed interlocutors we should almost always refrain from insisting on our controversial beliefs – with the few exceptions being all the more remarkable.

Unknown peers create a problem for those epistemologists who argue that we should be conciliatory in cases of peer disagreement. The standard interpretation of ‘being conciliatory’ has it that we should revise our opinions concerning a specific subject matter whenever we encounter someone who is as competent and well informed as we are concerning this subject matter (and thus is our peer) and holds a different opinion. As a consequence, peers whom we have never encountered and who are hence unknown to us are not taken into account. This, however, appears odd; not only because it is an accidental matter which peers we happen to encounter and which not, but also because it would allow people to deliberately isolate themselves from any kind of intellectual exchange on the topic under consideration. The paper argues that we should take the problem of unknown peers seriously, and that disregarding the problem is an instance of the more general mistake of assuming that evidential quality and justified believability can be dealt with separately. Moreover, a solution to the problem of unknown peers is suggested.

Dieser Text geht der Frage nach, ob und, wenn ja, inwieweit sich Gedankenexperimente in der praktischen Philosophie in ihrer Struktur und ihrer epistemischen Signifikanz von Gedankenexperimenten in der theoretischen Philosophie oder in den Naturwissenschaften unterscheiden. Anhand einer allgemeinen Strukturanalyse von Gedankenexperimenten wird dabei aufgezeigt, dass bei Gedankenexperimenten in der praktischen Philosophie zwar häufig die angemessene Bewertung eines zugrunde gelegten Szenarios im Zentrum steht und nicht, wie zum Beispiel in theoretischen Philosophie oft, dessen angemessene Beschreibung, dass dieser Unterschied aber kaum Auswirkungen hat auf die prinzipielle Anwendbarkeit – abgesehen von einer bisher übersehenen Konsequenz: Man darf in einem Gedankenexperiment nicht annehmen, dass moralische, ästhetische oder entscheidungstheoretische Prinzipien in unterschiedlichen möglichen Welten verschieden sind. Andernfalls käme dem Gedankenexperiment keinerlei epistemische Signifikanz zu.

The evidence that we get from peer disagreement is especially problematic from a Bayesian point of view since the belief revision caused by a piece of such evidence cannot be modelled along the lines of Bayesian conditionalisation. This paper explains how exactly this problem arises, what features of peer disagreements are responsible for it, and what lessons should be drawn for both the analysis of peer disagreements and Bayesian conditionalisation as a model of evidence acquisition. In particular, it is pointed out that the same characteristic of evidence from disagreement that explains the problems with Bayesian conditionalisation also suggests an interpretation of suspension of belief in terms of imprecise probabilities.

We are currently observing a shift in the relevance of ethical concerns regarding security screening systems. Due to technological progress, so my hypothesis goes, more direct consequences that such systems may have on the screening subjects' health and bodily privacy become increasingly unimportant compared to more indirect ones resulting from unrestrained information processing and excessive proliferation. However, a specific technical design of a screening system may help to prevent ethically unacceptable applications.

Können wir als Personen irreversible Gedächtnisverluste überleben? Wie steht es mit Teletransportationen? Wie mit jahrelangem Einfrieren? Fragen wie diese sind weit davon entfernt, bloße Denksportaufgaben für Science-Fiction-Fans zu sein. Vielmehr verraten uns Antworten darauf, welche unserer Eigenschaften uns wirklich wichtig sind und was unser Wesen ausmacht. Unglücklicherweise beantworten Vertreter unterschiedlicher Theorien personaler Identität diese Fragen auf völlig verschiedene Weise. Manche schöpfen die Plausibilität ihrer Positionen aus phantasievollen Gedankenexperimenten; anderen sind dieselben Gedankenexperimente für eine ernsthafte Einbeziehung in die philosophische Theoriebildung schlicht zu wirklichkeitsfern. Es überrascht daher kaum, dass jene Anhänger unterschiedlicher Theorien einander oft wenig zu sagen haben. Im ersten Teil des Buches wird untersucht, unter welchen Umständen Gedankenexperimente aussagekräftige philosophische Werkzeuge sind. Auf der Basis dieser Analyse werden die diversen zeitgenössischen Theorien personaler Identität dann im zweiten Teil einer Neubewertung unterzogen – nicht ohne dass dabei mit vielen selbstverständlich erscheinenden Überzeugungen aufgeräumt wird.

What philosophers have in mind when they think about vagueness are sorites cases. Unlike vague scientific or artificial expressions, however, vague natural language expressions do not display the kind of vagueness that we associate with the sorites; they rather display what I call cluster vagueness. A non-trivial consequence of this is that those legal definitions that state precisifications of natural language concepts not only add aspects of meaning to existing expressions but also effectively change the meanings of these expressions. From this, in turn, it follows that we should avoid precisifying ordinary expressions with the help of legal definitions to the extent that we wish legal language to be in line with natural language. And being in line with natural language may help us to deal with gaps in our laws at the very moment we become aware of them, and not just afterwards.

Theories of personal identity face a paradox, which traces back to Bernard Williams: some scenarios obviously show that mental continuity is what solely matters in survival; others, on the contrary, show with equal obviousness that it is bodily continuity. Different authors have produced diverging and partly conflicting answers in response to that problem. Based on recent research concerning the structure of philosophical thought experiment, this paper reevaluates and, for the first time, neatly classifies those answers. What is more, several existing approaches of how to answer the paradox are developed further, and two new answers are introduced.

A commonly neglected feature of the so-called Equal Weight View, according to which we should give our peers’ opinions the same weight we give our own, is its prima facie incompatibility with the common picture of philosophy as an armchair activity: an intellectual effort to seek a priori knowledge. This view seems to imply that our beliefs are more likely to be true if we leave our armchair in order to find out whether there actually are peers who, by disagreeing with us, force us to revise our beliefs. This article argues that the Equal Weight View should be spelled out in such a way that not only actual peer disagreement requires us to revise our beliefs, but also merely possible peer disagreement. This result is not a reductio ad absurdum of the view. Quite the opposite: it shows that the view is, contrary to appearance, compatible with our common way of doing philosophy.

Standardly, epistemic peers regarding a given matter are said to be people of equal competence who share all relevant evidence. Alternatively, one can define epistemic peers regarding a given matter as people who are equally likely to be right about that matter. I argue that a definition in terms of likelihood captures the essence of epistemic peerhood better than the standard definition or any variant of it. What is more, a likelihood definition implies the truth of the central thesis in the debate on peer disagreement, the so-called Equal Weight View, according to which we should give the opinions of our peers the same weight we give our own. Adopting a likelihood definition, however, does not end the debate on peer disagreement, because the alleged theoretical alternatives to the Equal Weight View, reinterpreted in the light of a likelihood definition, can in fact be shown to be compatible with this view—though the reinterpreted versions may appear less plausible than the original ones.

This paper outlines the often striking parallels of various approaches to ontic vagueness, as well as their even more striking differences. Though circling around the same idea, some of these approaches were developed to solve quite diverse theoretical problems and encounter different challenges. In addition to these difficulties, the frequently disregarded epistemological problems of all theories of ontic vagueness turn out to be even more serious under critical scrutiny. The same holds for the difficulties of deciding, for every case of vagueness, whether the vagueness involved is semantic or ontic.