In this paper we distinguish between various kinds of doxastic theories. One distinction is between informal and formal doxastic theories. AGM-type theories of belief change are of the former kind, while Hintikka’s logic of knowledge and belief is of the latter. Then we distinguish between static theories that study the unchanging beliefs of a certain agent and dynamic theories that investigate not only the constraints that can reasonably be imposed on the doxastic states of a rational agent but also rationality (...) constraints on the changes of doxastic state that may occur in such agents. An additional distinction is that between non-introspective theories and introspective ones. Non-introspective theories investigate agents that have opinions about the external world but no higher-order opinions about their own doxasticnstates. Standard AGM-type theories as well as the currently existing versions of Segerberg’s dynamic doxastic logic (DDL) are non-introspective. Hintikka-style doxastic logic is of course introspective but it is a static theory. Thus, the challenge remains to devise doxastic theories that are both dynamic and introspective. We outline the semantics for truly introspective dynamic doxastic logic, i.e., a dynamic doxastic logic that allows us to describe agents who have both the ability to form higher-order beliefs and to reflect upon and change their minds about their own (higher-order) beliefs. This extension of DDL demands that we give up the Preservation condition on revision. We make some suggestions as to how such a non-preservative revision operation can be constructed. We also consider extending DDL with conditionals satisfying the Ramsey test and show that Gärdenfors’ well-known impossibility result applies to such a framework. Also in this case, Preservation has to be given up. (shrink)

Festschrift for Michiel van Lambalgen on the occasion of his retirement as professor of logic and cognitive science at the University of Amsterdam.

In earlier papers (Lindström & Rabinowicz, 1989. 1990), we proposed a generalization of the AGM approach to belief revision. Our proposal was to view belief revision as a relation rather thanas a function on theories (or belief sets). The idea was to allow for there being several equally reasonable revisions of a theory with a given proposition. In the present paper, we show that the relational approach is the natural result of generalizing in a certain way an approach to belief (...) revision due to Adam Grove. In his (1988) paper, Grove presents two closely related modelings of functional belief revision, one in terms of a family of "spheres" around the agent's theory G and the other in terms of an epistemic entrenchment ordering of propositions. The "sphere"-terminology is natural when one looks upon theories and propositions as being represented by sets of possible worlds. Grove's spheres may be thought of as possible "fallback" theories relative to the agent's original theory: theories that he may reach by deleting propositions that are not "sufficiently" entrenched (according to standards of sufficient entrenchment of varying stringency). To put it differently, fallbacks are theories that are closed upwards under entrenchment The entrenchment ordering can be recovered from the family of fallbacks by the definition: A is at least as entrenched as B iff A belongs to every fallback to which B belongs. To revise a theory T with a proposition A, we go to the smallest sphere that contain A-worlds and intersect it with A. The relational notion of belief revision that we are interested in, results from weakening epistemic entrenchment by not assuming it to be connected. I.e., we want to allow that some propositions may be incomparable with respect to epistemic entrenchment. As a result, the family of fallbacks around a given theory will no longer have to be nested. This change opens up the possibility for several different ways of revising a theory with a given proposition. (shrink)

The theories of belief change developed within the AGM-tradition are not logics in the proper sense, but rather informal axiomatic theories of belief change. Instead of characterizing the models of belief and belief change in a formalized object language, the AGM-approach uses a natural language — ordinary mathematical English — to characterize the mathematical structures that are under study. Recently, however, various authors such as Johan van Benthem and Maarten de Rijke have suggested representing doxastic change within a formal logical (...) language: a dynamic modal logic. Inspired by these suggestions Krister Segerberg has developed a very general logical framework for reasoning about doxastic change: dynamic doxastic logic (DDL). This framework may be seen as an extension of standard Hintikka-style doxastic logic with dynamic operators representing various kinds of transformations of the agent's doxastic state. Basic DDL describes an agent that has opinions about the external world and an ability to change these opinions in the light of new information. Such an agent is non-introspective in the sense that he lacks opinions about his own belief states. Here we are going to discuss various possibilities for developing a dynamic doxastic logic for introspective agents: full DDL or DDL unlimited. The project of constructing such a logic is faced with difficulties due to the fact that the agent’s own doxastic state now becomes a part of the reality that he is trying to explore: when an introspective agent learns more about the world, then the reality he holds beliefs about undergoes a change. But then his introspective (higher-order) beliefs have to be adjusted accordingly. In the paper we shall consider various ways of solving this problem. (shrink)

“There is no use in trying,” said Alice; “one can’t believe impossible things.” “I dare say you haven’t had much practice,” said the Queen. “When I was your age, I always did it for half an hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”. Lewis Carroll, Through the Looking Glass. -/- It is a rather common view among philosophers that one cannot, properly speaking, be said to believe, conceive, imagine, hope for, or seek (...) what is impossible. -/- Some philosophers, for instance George Berkeley and the early Wittgenstein, thought that logically contradictory propositions lack cognitive meaning (informational content) and cannot, therefore, be thought or believed. Philosophers who do not go as far as Berkeley and Wittgenstein in denying that impossible propositions or states of affairs are thinkable, may still claim that it is impossible to rationally believe an impossible proposition. On a classical “Cartesian” view of belief, belief is a purely mental state of the agent holding true a proposition p that she “grasps” and is directly acquainted with. But if the agent is directly acquainted with an impossible proposition, then, presumably, she must know that it is impossible. But surely no rational agent can hold true a proposition that she knows is impossible. Hence, no rational agent can believe an impossible proposition. Thus it seems that on the Cartesian view of propositional attitudes as inner mental states in which proposition are immediately apprehended by the mind, it is impossible for a rational agent to believe, imagine or conceive an impossible proposition. -/- Ruth Barcan Marcus (1983) has suggested that a belief attribution is defeated once it is discovered that the proposition, or state of affairs that is believed is impossible. According to her intuition, just as knowledge implies truth, belief implies possibility. -/- It is commonplace that people claim to believe propositions that later turn out to be impossible. According to Barcan Marcus, the correct thing to say in such a situation is not: I once believed that A but I don’t believe it any longer since I have come to realize that it is impossible that A. What one should say is instead: It once appeared to me that I believed that A, but I did not, since it is impossible that A. Thus, Barcan Marcus defends what we might call Alice’s thesis: Necessarily, for any proposition p and any subject x, if x believes p, then p is possible. -/- Alice’s thesis that it is impossible to hold impossible beliefs, seems to come into conflict with our ordinary practices of attributing beliefs. Consider a mathematical example. Some mathematicians believe that CH (the continuum hypothesis) is true and others believe that it is false. But if CH is true, then it is necessarily true; and if it is false, then it is necessarily false. Regardless of whether CH is true or false, the conclusion seems to be that there are mathematicians who believe impossible propositions. -/- Examples of apparent beliefs in impossible propositions outside of mathematics are also easy to come by. Consider, for example, Kripke’s (1999) story of the Frenchman Pierre who without realizing it has two different names ‘London’ and ‘Londres’ for the same city, London. After having arrived in London, Pierre may assent to ‘Londres is beautiful and London is not beautiful’ without being in any way irrational. It seems reasonably to infer from this that Pierre believes that Londres is beautiful and London is not beautiful. But since ‘Londres’ and ‘London’ are rigid designators for the same city, it seems to follow from this that Pierre believes the inconsistent proposition that we may express as ‘London is both beautiful and not beautiful’. (shrink)

Modal logic is one of philosophy’s many children. As a mature adult it has moved out of the parental home and is nowadays straying far from its parent. But the ties are still there: philosophy is important to modal logic, modal logic is important for philosophy. Or, at least, this is a thesis we try to defend in this chapter. Limitations of space have ruled out any attempt at writing a survey of all the work going on in our field—a (...) book would be needed for that. Instead, we have tried to select material that is of interest in its own right or exemplifies noteworthy features in interesting ways. Here are some themes that have guided us throughout the writing: • The back-and-forth between philosophy and modal logic. There has been a good deal of give-and-take in the past. Carnap tried to use his modal logic to throw light on old philosophical questions, thereby inspiring others to continue his work and still others to criticise it. He certainly provoked Quine, who in his turn provided—and continues to provide—a healthy challenge to modal logicians. And Kripke’s and David Lewis’s philosophies are connected, in interesting ways, with their modal logic. Analytic philosophy would have been a lot different without modal logic! • The interpretation problem. The problem of providing a certain modal logic with an intuitive interpretation should not be conflated with the problem of providing a formal system with a model-theoretic semantics. An intuitively appealing model-theoretic semantics may be an important step towards solving the interpretation problem, but only a step. One may compare this situation with that in probability theory, where definitions of concepts like ‘outcome space’ and ‘random variable’ are orthogonal to questions about “interpretations” of the concept of probability. • The value of formalisation. Modal logic sets standards of precision, which are a challenge to—and sometimes a model for—philosophy. Classical philosophical questions can be sharpened and seen from a new perspective when formulated in a framework of modal logic. On the other hand, representing old questions in a formal garb has its dangers, such as simplification and distortion. • Why modal logic rather than classical (first or higher order) logic? The idioms of modal logic—today there are many!—seem better to correspond to human ways of thinking than ordinary extensional logic. (Cf. Chomsky’s conjecture that the NP + VP pattern is wired into the human brain.) In his An Essay in Modal Logic (1951) von Wright distinguished between four kinds of modalities: alethic (modes of truth: necessity, possibility and impossibility), epistemic (modes of being known: known to be true, known to be false, undecided), deontic (modes of obligation: obligatory, permitted, forbidden) and existential (modes of existence: universality, existence, emptiness). The existential modalities are not usually counted as modalities, but the other three categories are exemplified in three sections into which this chapter is divided. Section 1 is devoted to alethic modal logic and reviews some main themes at the heart of philosophical modal logic. Sections 2 and 3 deal with topics in epistemic logic and deontic logic, respectively, and are meant to illustrate two different uses that modal logic or indeed any logic can have: it may be applied to already existing (non-logical) theory, or it can be used to develop new theory. (shrink)

Enligt ett realistiskt synsätt kan ett påstående vara sant trots att det inte ens i princip är möjligt att veta att det är sant. En sanningsteoretisk antirealist kan inte godta denna möjlighet utan accepterar en eller annan version av Dummetts vetbarhetsprincip: (K) Om ett påstående är sant, så måste det i princip vara möjligt att veta att det är sant. Det kan dock förefalla rimligt, även för en antirealist, att gå̊ med på̊ att det kan finnas sanningar som ingen faktiskt (...) vet (har vetat, eller kommer att veta) är sanna. Man kan därför tänka sig att en antirealist skulle acceptera principen (K) utan att därför gå med på den till synes starkare principen: (SK) Om ett påstående är sant, så måste det faktiskt finnas någon som vet att det är sant. Ett mycket omdiskuterat argument – som ytterst går tillbaka till Alonzo Church, men som först publicerades i en uppsats av Frederic Fitch i Journal of Symbolic Logic 1963 – tycks emellertid visa att principen (K) implicerar principen (SK). Anta nämligen att (K) är sann, medan (SK) inte är det. Men om (SK) är falsk, så finns det ett påstående som är sant men som ingen faktiskt vet är sant. Anta nu att p är ett sådant påstående. Låt Kp betyda att någon vet att p är sant. Det galler alltså̊ att p är sant samtidigt som Kp inte är det. Betrakta nu påståendet (p ∧ −Kp). Enligt antagandet är detta påstående sant. Enligt (K) måste det då vara möjligt att någon vet att (p ∧ −Kp). D.v.s., det måste vara möjligt att påståendet K(p ∧ −Kp) är sant. Men i så fall är det också̊ möjligt att påståendet Kp ∧ K−Kp är sant, vilket i sin tur implicerar att det är möjligt att Kp ∧ −Kp är sant, vilket ju är absurt. Således kan inte (K) vara sann samtidigt som (SK) är falsk. Vi tycks således kunna sluta oss till att (K) implicerar (SK). I uppsatsen diskuterar jag några olika sätt att undgå̊ Church-Fitch paradoxala slutsats. Ett tillvägagångssätt är att ersätta kunskapsoperatorn med en hierarki av kunskapspredikat. Ett annat är baserat på distinktionen mellan faktisk och potentiell kunskap och ett förkastande av den vanliga modallogiska formaliseringen av principen (K). Den senare typen av lösning betraktas både från ett realistiskt och ett icke-realistiskt perspektiv. Utifrån denna analys kommer jag fram till slutsatsen att vi, vare sig vi är realister eller antirealister rörande sanning, kan sluta oroa oss för vetbarhetsparadoxen och ändå uppskatta Church-Fitchs argument. (shrink)

This paper presents a uniform semantic treatment of nonmonotonic inference operations that allow for inferences from infinite sets of premises. The semantics is formulated in terms of selection functions and is a generalization of the preferential semantics of Shoham (1987), (1988), Kraus, Lehman, and Magidor (1990) and Makinson (1989), (1993). A selection function picks out from a given set of possible states (worlds, situations, models) a subset consisting of those states that are, in some sense, the most preferred ones. A (...) proposition α is a nonmonotonic consequence of a set of propositions Γ iff α holds in all the most preferred Γ-states. In the literature on revealed preference theory, there are a number of well-known theorems concerning the representability of selection functions, satisfying certain properties, in terms of underlying preference relations. Such theorems are utilized here to give corresponding representation theorems for nonmonotonic inference operations. At the end of the paper, the connection between nonmonotonic inference and belief revision, in the sense of Alchourrón, Gärdenfors, and Makinson, is explored. In this connection, infinitary belief revision operations that allow for the revision of a theory with a possibly infinite set of propositions are introduced and characterized axiomatically. (shrink)

Goethe carried out an enormous number of experiments before criticizing Newton's theory of light and colours in the Farbenlehre (1810). He managed to show that Newton's reasoning is based on a rather narrow choice of experiments, in which parameters such as the distance between the prism and the screen are fixed arbitrarily: Newton's famous spectrum (with its green centre) occurs only at a specific distance. Once you reduce the distance, the green centre disappears, and you see the two border spectra (...) instead. Newton can of course explain these border spectra; but things can be explained just as well the other way around: Then you start with a theory based on the two border spectra in order to derive the Newtonian spectrum. Both accounts fit many data (available in Newton and Goethe's days) equally well. Thus by insisting that the step to theory is not forced upon us by "reason and experiments" alone (as Newton would have it), Goethe revealed our own free, creative contribution to theory construction. And surprisingly, his theory of the prismatic colours seems no worse off than Newton's, even taking into account additional criteria of theory choice, such as simplicity or elegance. (shrink)

In the late summer of 1998, the authors, a cognitive scientist and a logician, started talking about the relevance of modern mathematical logic to the study of human reasoning, and we have been talking ever since. This book is an interim report of that conversation. It argues that results such as those on the Wason selection task, purportedly showing the irrelevance of formal logic to actual human reasoning, have been widely misinterpreted, mainly because the picture of logic current in psychology (...) and cognitive science is completely mistaken. We aim to give the reader a more accurate picture of mathematical logic and, in doing so, hope to show that logic, properly conceived, is still a very helpful tool in cognitive science. The main thrust of the book is therefore constructive. We give a number of examples in which logical theorizing helps in understanding and modeling observed behavior in reasoning tasks, deviations of that behavior in a psychiatric disorder (autism), and even the roots of that behavior in the evolution of the brain. (shrink)

Goethe's objections to Newton's theory of light and colours are better than often acknowledged. You can accept the most important elements of these objections without disagreeing with Newton about light and colours. As I will argue, Goethe exposed a crucial weakness of Newton's methodological self-assessment. Newton believed that with the help of his prism experiments, he could prove that sunlight was composed of variously coloured rays of light. Goethe showed that this step from observation to theory is more problematic than (...) Newton wanted to admit. By insisting that the step to theory is not forced upon us by the phenomena, Goethe revealed our own free, creative contribution to theory construction. And Goethe's insight is surprisingly significant, because he correctly claimed that all of the results of Newton's prism experiments fit a theoretical alternative equally well. If this is correct, then by suggesting an alternative to a well-established physical theory, Goethe developed the problem of underdete... (shrink)

Quine claims that holism (i.e., the Quine-Duhem thesis) prevents us from defining synonymy and analyticity (section 2). In Word and Object, he dismisses a notion of synonymy which works well even if holism is true. The notion goes back to a proposal from Grice and Strawson and runs thus: R and S are synonymous iff for all sentences T we have that the logical conjunction of R and T is stimulus-synonymous to that of S and T. Whereas Grice and Strawson (...) did not attempt to defend this definition, I try to show that it indeed gives us a satisfactory account of synonymy. Contrary to Quine, the notion is tighter than stimulus-synonymy – particularly when applied to sentences with less than critical semantic mass (section 3). Now according to Quine, analyticity could be defined in terms of synonymy, if synonymy were to make sense: A sentence is analytic iff synonymous to self-conditionals. This leads us to the following notion of analyticity: S is analytic iff, for all sentences T, the logical conjunction of S and T is stimulus-synonymous to T; an analytic sentence does not change the semantic mass of any theory to which it may be conjoined (section 4). This notion is tighter than Quine's stimulus-analyticity; unlike stimulus-analyticity, it does not apply to those sentences from the very center of our theories which can be assented to come what may, even though they are not synthetic in the intuitive sense (section 5). Conclusion: We can have well-defined notions of synonymy and analyticity even if we embrace Quine's holism, naturalism, behaviorism, and radical translation. Quine's meaning skepticism is to be repudiated on Quinean grounds. (shrink)

Quine's early arguments in favor of "Ontological Relativity" depend on wild but interesting alternatives to standard ontology,most apparent when viewing his unusual idea of undetached object parts. In Quine's later philosophy, by contrast, he invokes trivial proxy functions and simple permutations to standard ontology, and in so doing paves the way for his claim of "Inscrutability of Reference". Nevertheless, Quine's more recent alternatives to standard ontology have thus far remained uninteresting for ontological questions, as his later arguments fail to offer (...) any real alternative to our standard identity relation. For this reason, I have chosen to return to Quine's original idea of "Ontological Relativity" and put it to the test. In my investigation, development and subsequent defense of Quine's original presentation, I attempt to show that it is in fact possible to read Quine's ontology of undetached object parts into a large sphere of our language. (shrink)

Bradford Hill (1965) highlighted nine aspects of the complex evidential situation a medical researcher faces when determining whether a causal relation exists between a disease and various conditions associated with it. These aspects are widely cited in the literature on epidemiological inference as justifying an inference to a causal claim, but the epistemological basis of the Hill aspects is not understood. We offer an explanatory coherentist interpretation, explicated by Thagard's ECHO model of explanatory coherence. The ECHO model captures the complexity (...) of epidemiological inference and provides a tractable model for inferring disease causation. We apply this model to three cases: the inference of a causal connection between the Zika virus and birth defects, the classic inference that smoking causes cancer, and John Snow’s inference about the cause of cholera. (shrink)

We discuss various possibilities for developing a dynamic doxastic logic (DDL) for introspective agents: agents who have the ability to form higher-order beliefs. Such agents can reflect upon and change their minds about their own beliefs. The project of constructing such a logic, full DDL or DDL unlimited, is ridden with difficulties due to the fact that the agent's own doxastic state now becomes a part of the reality he is trying to explore. When an introspective agent learns more about (...) the world (and himself), the reality he holds beliefs about undergoes a change in its doxastic part, which means that his introspective beliefs have to be adjusted accordingly. (shrink)

In this paper, I shall consider the challenge that Quine posed in 1947 to the advocates of quantified modal logic to provide an explanation, or interpretation, of modal notions that is intuitively clear, allows “quantifying in”, and does not presuppose, mysterious, intensional entities. The modal concepts that Quine and his contemporaries, e.g. Carnap and Ruth Barcan Marcus, were primarily concerned with in the 1940’s were the notions of (broadly) logical, or analytical, necessity and possibility, rather than the metaphysical modalities that (...) have since become popular, largely due to the influence of Kripke. In the 1950’s modal logicians responded to Quine’s challenge by providing quantified modal logic with model-theoretic semantics of various types. In doing so they also, explicitly or implicitly addressed Quine’s interpretation problem. Here I shall consider the approaches developed by Carnap in the late 1940’s, and by Kanger, Hintikka, Montague, and Kripke in the 1950’s, and discuss to what extent these approaches were successful in meeting Quine’s doubts about the intelligibility of quantified modal logic. (shrink)

The search for causes of perinatal brain damage needs a solid theoretical foundation. Current theory apparently does not offer a unanimously accepted view of what constitutes a cause, and how it can be identified. We discuss nine potential theoretical misconceptions: (1) too narrow a view of what is a cause (causal production vs. facilitation), (2) extrapolating from possibility to fact (potential vs. factual causation), (3) if X, then invariably Y (determinism vs. probabilism), (4) co-occurrence in individuals vs. association in populations, (...) (5) one cause is all that is needed (single cause attribution vs. multicausal constellations), (6) drawing causal inferences from very small numbers of observations (the tendency to generalize), (7) unstated causal inferences, (8) ignoring heterogeneity, and (9) failing to consider alternative explanations for what is observed. We hope that our critical discussion will contribute to fruitful research and help reduce the burden of perinatal brain damage. (shrink)

Wie müsste eine faire Lösung des Klimaproblems aussehen? Wie sollten wir Pflichten und finanzielle Lasten der nötigen CO2-Reduktionen verteilen, wenn es dabei gerecht zugehen soll und keiner übervorteilt werden darf? In meiner Antwort auf diese ethischen Fragen stütze ich mich auf einen Grundsatz, den Angela Merkel formuliert hat: Jeder Mensch hat das Recht, genauso viel CO2-Emissionen zu verursachen wie jeder andere. Anders als die Bundeskanzlerin, die den Grundsatz nur langfristig in die Tat umsetzen will, plädiere ich dafür, dass die Gleichberechtigung (...) aller in Sachen CO2-Ausstoß schon unter dem Nachfolge-Regime des Kyoto-Vertrags gelten soll. In einem ersten Schritt soll die Steigerung der weltweiten CO2-Emissionen angehalten werden. Um das auf gerechte Weise zu bewerkstelligen, werden in feiner Stückelung Rechte zum CO2-Ausstoß (die sog. Mikro-Zertifikate) ausgegeben, und zwar zunächst für genau so viel CO2, wie die Menschheit zur Zeit insgesamt pro Jahr in die Luft bläst. Wer CO2 emittieren will, gleichgültig wo, wie und wozu, darf das nur gegen Entwertung einer entsprechenden Anzahl an Mikro-Zertifikaten, sonst macht er sich strafbar. Die Mikro-Zertifikate werden auf einer weltweiten Börse gehandelt; ihr Preis ergibt sich aus Angebot und Nachfrage. Mein Vorschlag unterscheidet sich in zweierlei Hinsicht von den Versteigerungen der CO2-Zertifikate, wie sie bislang konzipiert und organisiert worden sind. Einerseits sollen am Ende alle Emissionen klimaschädlicher Gase in den Handel mit Mikro-Zertifikaten einbezogen werden. Andererseits wird das Geld, das durch die Versteigerung der Mikro-Zertifikate zusammenkommt, in regelmäßigen Abständen und ohne Abzüge an jeden einzelnen Menschen ausgezahlt. Das ist einfach, fair und transparent. In einem zweiten Schritt sind die weltweiten CO2-Emissionen drastisch zu verringern: Nach einer siebenjährigen Verschnaufpause (in der sich Produzenten und Verbraucher auf die erforderlichen Anpassungen vorbereiten können) beginnen die sieben dürren Jahre der CO2-Politik: Jahr für Jahr werden 10% weniger Mikro-Zertifikate ausgegeben. Am Ende dieser Durststrecke haben sich die weltweiten CO2-Emissionen halbiert, und die Klima-Investitionen sind dahin geflossen, wo sie dem Klima am stärksten nutzen und wo das am wenigsten Kapital verschlingt. (shrink)

Theory of illness causation is an important issue in all biomedical sciences, and solid etiological explanations are needed in order to develop therapeutic approaches in medicine and preventive interventions in public health. Until now, the literature about the theoretical underpinnings of illness causation research has been scarce and fragmented, and lacking a convenient summary. This interdisciplinary book provides a convenient and accessible distillation of the current status of research into this developing field, and adds a personal flavor to the discussion (...) by proposing the etiological stance as a comprehensive approach to identify modifiable causes of illness. (shrink)

Man kann die Unterscheidung zwischen synthetischen und analytischen Sätzen aus zwei Perspektiven betrachten – von innen oder von außen: mit Blick auf die eigene Sprache oder mit Blick auf die Sprache anderer. Wer die Außenperspektive einnimmt, sucht eine Antwort auf die deskriptive Frage, welche Sätze einer fremden Sprache als analytisch zu klassifizieren sind. Wer die Innenperspektive einnimmt, sucht dagegen eine Antwort auf folgende normative Frage: Welche Sätze darf ich nicht preisgeben oder zurückweisen – wenn ich keinen Unfug reden will? Die (...) beiden Blickwinkel schließen einander nicht aus; sie ergänzen sich und unterstützen einander. In seinem Aufsatz „Two dogmas of empiricism“ kritisiert Quine die Unterscheidung zwischen synthetischen und analytischen Sätzen aus der Innenperspektive; in seinem Buch Word and object wiederholt er dieselbe Kritik aus der Außenperspektive. In beiden Fällen richtet sich seine Kritik gegen die Ziele des frühen Carnap (der sämtliche Ausdrücke der Wissenschaftssprache mithilfe analytisch wahrer Definitionen verständlich machen wollte). Ich trete beiden Fassungen dieser Kritik entgegen und schlage zwei Definitionen des Begriffs vom analytischen Satz vor, die Quines Kritik entgehen: eine Definition aus der Außen- und eine aus der Innenperspektive. Zum Abschluss führe ich in einer leicht spekulativen Betrachtung vor, wie man bloßen Begriffswandel vom Wandel der inhaltlichen Überzeugungen trennen könnte – und zwar sogar im Fall wissenschaftlicher Revolutionen. (shrink)

Pacifists and their opponents disagree not only about moral questions, but rather often about factual questions as well—as seen when looking at the controversy surrounding the crisis in Kosovo. According to my reconstruction of pacifism, this is not surprising since the pacifist,legitimately, looks at the facts in the light of her system of value. Her opponent, in turn, looks at the facts in the light of an alternative value system, and the quarrel between the two parties about supposedly descriptive matters (...) never ceases, as there is no objective reality about the war in question that could settle the issue.In my view, the pacifist's value-laden way of looking at reality implicitly obeys three epistemic imperatives. First, the Epistemic Imperative concerning Human Nature ("Resist demonizing the other side; always try to understand the case from the other point of view"). Second, the Epistemic Imperative concerning Non-Violent Alternatives ("Always search for non-violent alternatives to military action"). Third, the Epistemic Imperative concerning Uncontrolled Escalation ("Hone your senses to the uncontrolled, irreversible side effects of military action, particularly to the danger of military escalation leading to another world war"). Objective reality has no way of telling us how far we should go in following these imperatives. Rather, we have to make the decision about how far we are going to take them ourselves. In this way, the pacifist's epistemic imperatives are comparable to Kant's regulative principles. (shrink)

In its reaction on the terroristic attacks of September 9th, 2001, the US-government threatened Afghanistan's Taleban with war in order to force them to extradite terrorist leader Bin Laden; the Taleban said that they would not surrender to this kind of blackmail – and so, they were removed from Kabul by means of military force. The rivalling versions of this story depend crucially on notions such as "terrorism" and "blackmail". Obviously you'll gain public support for your preferrend version of the (...) story if you are able to determine how those notions are to be used. So we had better reflect about their very meaning and about the moral implications of their proper usage. To gain a deeper understanding of our notions of "blackmail" and "terrorism" I shall propose an extreme thought experiment: Cassandra's plan. Cassandra foresees that sooner or later one of the nuclear powers might take the liberty to use atomic bombs. From fright she founds an NGO for blackmailing the statesmen who are in charge of nuclear weapons; she announces in public that all ministers and leaders of any government shall be hunted down, and executed, whose soldiers drop but one atomic bomb. (Cassandra's NGO keeps killer teams in constant training so as to increase the effect of the threat; this is being financiated from private donations). In my paper I shall raise two questions (without claiming to provide definite answers). First, would we have to say that Cassandra's NGO was a terrorist organisation? Second, would it be morally wrong if Cassandra blackmailed statesmen in the way indicated? (shrink)

At the core of medicine is the idea to help fellow human beings by improving or even restoring their health. Let us call this the auxiliary stance of medicine—the motivation of medical intervention by reference to a moral obligation to guide our peers in their attempt to live a healthy and productive life. In parallel, the auxiliary stance is also central to public health, with a focus on prevention and health promotion. Taken together, we can view medicine and public health (...) as the two main human auxiliary endeavors to protect individuals and populations from health risks and help them to heal when sick. (shrink)

We use quotation marks when we wish to refer to an expression. We can and do so refer even when this expression is composed of characters that do not occur in our alphabet. That's why Tarski, Quine, and Geach's theories of quotation don't work. The proposals of Davidson, Frege, and C. Washington, however, do not provide a plausible account of quotation either. (Section I). The problem is to construct a Tarskian theory of truth for an object language that contains quotation (...) marks, without appealing to quotation marks in the metalanguage. I propose to supply Tarski's truth definition with one axiom that determines the denotation of all expressions containing quotation marks. According to this axiom, quotation marks create a non-extensional context. Since admitting such contexts does not lead to any difficulties in the recursive truth characterization, we may indeed dispense with extensionalism. (Section II). Finally, I argue that we classify and denote expressions in the very same way that we classify and denote extralinguistic entities. Both tokens and types of written signs can be easily incorporated into the naturalist's worldview. (Section III). (shrink)

Pacifists and their opponents disagree not only about moral questions, but most often about factual questions as well. For example, they came to divergent descriptions of the crisis in Kosovo. According to my reconstruction of pacifism, this is not a surprise because the pacifist, legitimately, looks at the facts in the light of her system of value. Her opponent, in turn, looks at the facts in the light of alternative systems of value, and the quarrel between the two parties about (...) supposedly descriptive matters does not come to an end as there is no objective reality about the war in question that could settle the issue. If I am right, the pacifist's value-laden way of looking at reality can be reconstructed as an obedience to three epistemic imperatives. First, the Epistemic Imperative concerning Human Nature ("Resist against demonizing the other side; always try to understand the case from their point of view"). Second, the Epistemic Imperative concerning Non-Violent Alternatives ("Always search for non-violent alternatives to projected military action"). Third, the Epistemic Imperative concerning Uncontrolled Escalation ("Sharpen your attention for uncontrolled, irreversible side effects of military action, particularly for the danger of escalation to another world war"). Objective reality does not decide how far one should go in following these imperatives. Rather, the decision about this is our's—similarly as in case of the scientist who decides to search for common deep structure behind the chaos of the manifold. So the pacifist's epistemic imperatives can be compared to Kant's regulative principles that are necessary for guiding the scientific scrutiny of reality. (shrink)

The analytic/synthetic distinction can be conceived from two points of view: from within or from without; from the perspective of one's own language or from the perspective of the language of others. From without, the central question is which sentences of a foreign language are to be classified as analytic. From within, by contrast, the question concerning the synthetic and the analytic acquires a normative dimension: which sentences am I not permitted to reject—if I want to avoid talking nonsense? Both (...) perspectives on analytic sentences do not mutually exclude but supplement and illuminate each other. In "Two Dogmas", Quine's criticism of the analytic/synthetic distinction comes from within, whereas in Word and Object, Quine repeats his earlier criticism from without. His criticism is directed against Carnap's views on our understanding of theoretical terms. I challenge Quine's criticism in both of its versions and provide two definitions for analyticity that are immune to Quine's arguments. Using the first of these definitions (the one from without) I try to show how it is possible to distinguish (genuine) belief revision from linguistic change—even in case of a scientific revolution. (shrink)

Worin besteht Mills Argument für den Utilitarismus? Im psychologischen Teil des Arguments plädiert Mill für eine aggregierte Beschreibung unserer hedonistischen Werte ("Das allgemeine Glück ist ein Gut für die Gesamtheit aller Personen"). Von hier aus steuert er im normativen Teil des Arguments auf eine aggregierte Bewertung zu ("Das allgemeine Glück ist ein Gut"). Mills Übergang von Beschreibung zu Wertung beruht auf zwei versteckten Annahmen: Die erste sagt (gegen den Nihilisten), dass es Werte gibt; die zweite sagt (gegen Wert-Metaphysiker), dass die (...) Antwort auf die Frage nach Werten nicht völlig unabhängig von dem sein kann, was wir alle de facto für wert erachten. Diese beiden Voraussetzungen scheinen keine inhaltlichen Aussagen zur Moral zu enthalten. Doch wer sie teilt, wird von Mills Argument überraschend weit in die Gefilde der Moral getrieben. Sein Argument ist besser, als die meisten Interpreten glauben. (shrink)

Quine claims that holism (i.e., the Quine-Duhem thesis) prevents us from defining synonymy and analyticity (section 2). In "Word and Object," he dismisses a notion of synonymy which works well even if holism is true. The notion goes back to a proposal from Grice and Strawson and runs thus: R and S are synonymous iff for all sentences T we have that the logical conjunction of R and T is stimulus-synonymous to that of S and T. Whereas Grice and Strawson (...) did not attempt to defend this definition, I try to show that it indeed gives us a satisfactory account of synonymy. Contrary to Quine, the notion is tighter than stimulus-synonymy -- particularly when applied to sentences with less than critical semantic mass (section 3). Now according to Quine, analyticity could be defined in terms of synonymy, if synonymy were to make sense: A sentence is analytic iff synonymous to self-conditionals. This leads us to the following notion of analyticity: S is analytic iff, for all sentences T, the logical conjunction of S and T is stimulus-synonymous to T; an analytic sentence does not change the semantic mass of any theory to which it may be conjoined (section 4). This notion is tighter than Quine's stimulus-analyticity; unlike stimulus-analyticity, it does not apply to those sentences from the very center of our theories which can be assented to come what may, even though they are not synthetic in the intuitive sense (section 5). (shrink)

The main objective of this paper is to examine how theories of truth and reference that are in a broad sense Fregean in character are threatened by antinomies; in particular by the Epimenides paradox and versions of the so-called Russell-Myhill antinomy, an intensional analogue of Russell’s more well-known paradox for extensions. Frege’s ontology of propositions and senses has recently received renewed interest in connection with minimalist theories that take propositions (thoughts) and senses (concepts) as the primary bearers of truth and (...) reference. In this paper, I will present a rigorous version of Frege’s theory of sense and denotation and show that it leads to antinomies. I am also going to discuss ways of modifying Frege’s semantical and ontological framework in order to avoid the paradoxes. In this connection, I explore the possibility of giving up the Fregean assumption of a universal domain of absolutely all objects, containing in addition to extensional objects also abstract intensional ones like propositions and singular concepts. I outline a cumulative hierarchy of Fregean propositions and senses, in analogy with Gödel’s hierarchy of constructible sets. In this hierarchy, there is no domain of all objects. Instead, every domain of objects is extendible with new objects that, on pain of contradiction, cannot belong to the given domain. According to this approach, there is no domain containing absolutely all propositions or absolutely all senses. (shrink)

Dieser Aufsatz beschreibt und erörtert fünf Aspekte der gegenwärtigen Wissenschaft: Verfahren, Zwiespalt, Schweigen, Hoffnung, und Probieren.

Nach Morton White können wir die holistische Quine/Duhem-These auf ethische Sätze genauso anwenden wie auf wissenschaftliche. Demzufolge mögen sich die meisten ethische Sätze zwar nicht einzeln testen lassen, wohl aber im Zusammenhang einer kompletten Theorie, die sowohl deskriptive als auch normative Sätze enthält. Ich diskutiere zwei Vorschläge dafür, wie dieser Vergleich durchbuchstabiert werden könnte. Laut Whites eigenem Vorschlag lassen sich einige normative Konsequenzen des Gesamtsystems durch Konfrontation mit den emotionalen Reaktionen des Sprechers testen. Laut meinem Vorschlag sind einige normative Konsequenzen (...) des Systems bereits Beobachtungssätze in Quines Sinn und können genauso getestet werden wie naturwissenschaftliche Beobachtungssätze, nämlich durch Sinneserfahrung. Kurzum, es gibt moralische Beobachtungssätze. Quine bezeichnet diejenigen Sätze als Beobachtungssätze, die alle anwesenden Sprecher einer Gemeinschaft stets gleich beurteilen und die der einzelne Sprecher ausschließlich aufgrund momentaner Sinnesreizung bejaht oder verneint (also unabhängig von Hintergrund-Informationen). In Quines Argument gegen moralische Beobachtungssätze steckt folgender Fehler: Quine glaubt, dass sich moralische Fragen immer nur angesichts von Hintergrund-Informationen beurteilen lassen. Bei vielen moralischen Sätzen mag das so sein; aber es gibt Gegenbeispiele, in denen Hintergrund-Informationen ausgeschaltet sind, z.B. "Dies ist sichtbares Unrecht". (shrink)

Let us imagine an ideal ethical agent, i.e., an agent who (i) holds a certain ethical theory, (ii) has all factual knowledge needed for determining which action among those open to her is right and which is wrong, according to her theory, and who (iii) is ideally motivated to really do whatever her ethical theory demands her to do. If we grant that the notions of omniscience and ideal motivation both make sense, we may ask: Could there possibly be an (...) ideal utilitarian, that is, an ideal ethical agent whose ethical theory says that our only moral obligation consists in maximizing utility? I claim that an ideal agent cannot be utilitarian. My reasoning against ideal utilitarianism will parallel Putnam's famous argument against the brains in a vat. Putnam argues that an envatted brain cannot describe its own situation because its words do not refer to brains and vats; I argue that an ideal utilitarian cannot entertain or communicate the beliefs necessary to being a utilitarian. (shrink)

Aristotle’s words in the Metaphysics: “to say of what is that it is, or of what is not that it is not, is true” are often understood as indicating a correspondence view of truth: a statement is true if it corresponds to something in the world that makes it true. Aristotle’s words can also be interpreted in a deflationary, i.e., metaphysically less loaded, way. According to the latter view, the concept of truth is contained in platitudes like: ‘It is true (...) that snow is white iff snow is white’, ‘It is true that neutrinos have mass iff neutrinos have mass’, etc. Our understanding of the concept of truth is exhausted by these and similar equivalences. This is all there is to truth. In his book Truth (Second edition 1998), Paul Horwich develops minimalism, a special variant of the deflationary view. According to Horwich’s minimalism, truth is an indefinable property of propositions characterized by what he calls the minimal theory, i.e., all (nonparadoxical) propositions of the form: It is true that p if and only if p. Although the idea of minimalism is simple and straightforward, the proper formulation of Horwich’s theory is no simple matter. In this paper, I shall discuss some of the difficulties of a logical nature that arise. First, I discuss problems that arise when we try to give a rigorous characterization of the theory without presupposing a prior understanding of the notion of truth. Next I turn to Horwich’s treatment of the Liar paradox and a paradox about the totality of all propositions that was first formulated by Russell (1903). My conclusion is that Horwich’s minimal theory cannot deal with these difficulties in an adequate way, and that it has to be revised in fundamental ways in order to do so. Once such revisions have been carried out the theory may, however, have lost some of its appealing simplicity. (shrink)

Using as case studies two early diagrams that represent mechanisms of the cell division cycle, we aim to extend prior philosophical analyses of the roles of diagrams in scientific reasoning, and specifically their role in biological reasoning. The diagrams we discuss are, in practice, integral and indispensible elements of reasoning from experimental data about the cell division cycle to mathematical models of the cycle’s molecular mechanisms. In accordance with prior analyses, the diagrams provide functional explanations of the cell cycle and (...) facilitate the construction of mathematical models of the cell cycle. But, extending beyond those analyses, we show how diagrams facilitate the construction of mathematical models, and we argue that the diagrams permit nomological explanations of the cell cycle. We further argue that what makes diagrams integral and indispensible for explanation and model construction is their nature as locality aids: they group together information that is to be used together in a way that sentential representations do not. (shrink)

Die Skeptikerin fragt, wie wir ausschließen können, dass all unsere Erlebnisse auf einem umfassenden Traum beruhen. Träfe ihre Befürchtung zu, dann wären alle unsere Meinungen über die äußere Welt falsch, und da wir das nicht ausschließen können, haben wir (so folgert sie) keinerlei Wissen über die Welt. Um dem zu begegnen, könnte man der Skeptikerin vorwerfen, dass sie unsere gemeinsame Sprache missbraucht. Welche Wörter missbraucht sie? Welche Wörter gebraucht sie so anders, dass wir uns um ihre Überlegung nicht scheren müssen? (...) Ich spiele das sprachkritische Manöver gegen die Skeptikerin zunächst anhand des Wissensbegriffs durch (und komme zu dem Ergebnis, dass wir nicht klar genug sagen können, worin die unstrittige Bedeutung des Wortes "Wissen" besteht). Dann versuche ich es mit weniger tiefsinnigen Wörtern wie "Tiger". Wer stets träumt, gebraucht solche Wörter anders als wir, so die Überlegung. Dieser Gedanke funktioniert nur, wenn wir die Existenz von Außenwelt-Dingen voraussetzen dürfen; und diese Voraussetzung bestreitet die Skeptikerin. Daher spiele ich das sprachkritische Manöver zuguterletzt anhand des Traumbegriffs durch. Jemand kann das Wort "Traum" überhaupt nur dann gelernt haben, wenn er manchmal, aber nicht immer geträumt hat. Ergebnis: Entweder ich verstehe das Wort "Traum". Dann träume ich nicht seit jeher. Oder ich verstehe das Wort nicht. Dann brauche ich mich vom Traum-Argument auch nicht an meinen Wissens-Ansprüchen irre machen zu lassen. (shrink)