The theory of nomic probability

This article sketches a theory of objective probability focusing on nomic probability, which is supposed to be the kind of probability figuring in statistical laws of nature. The theory is based upon a strengthened probability calculus and some epistemological principles that formulate a precise version of the statistical syllogism. It is shown that from this rather minimal basis it is possible to derive theorems comprising (1) a theory of direct inference, and (2) a theory of induction. The theory of induction is not of the familiar Bayesian variety, but consists of a precise version of the traditional Nicod Principle and its statistical analogues.     

ARMSTRONG AND THE MODAL INVERSION OF DISPOSITIONS

D.M. Armstrong has objected that the dispositionalist theory of laws and properties is modally inverted, for it entails that properties are constituted by relations to non-actual possibilia. I contend that if this objection succeeds against dispositionalism, then Armstrong's nomic necessitation relation is also modally inverted. This shows that at least one of Armstrong's reasons for preferring a nomic necessitation theory is specious.     

Logical versus psychological necessity: A discussion of the role of common sense in psychological theory

Smedslund's has argued that psychological theory should be concerned with the logical analysis of common sense since (a) empirical data are "arbitrary" and no general and empirical laws can exist when it comes to human action; and (b) theoretical explanation of data is likely to be empirically empty—psychological theory often cannot be falsified. The argument was supported mainly by an analysis of Bandura's self-efficacy conceptions. Bandura's approach is, however, not developed to the point of being an explicit theory, a fact that explains why it can be demonstrated as being non-distinguishable from the naive analysis of action. Many well developed theories of decision making, such as Tversky's EBA theory, transcend common sense and are falsifiable. Common sense is, furthermore, subject to change over time and differs between cultures, and even between individuals. There is no such things as the common sense. It is also inconsistent and ambiguous and uses a loose mode of thinking which can often provide post hoc explanations but no predictions. Therefore, common sense probably offers little in the way of profound insights. Furthermore, the problems of inferrring general laws from unique events have not stifled progress in the natural sciences and should not discourage psychologists. The case for general laws in psychology is still being heard. Besides, even if findings are restricted in time and space they concern important questions of how people act here and now. Finally, Smedslund's attempt at logical analysis of treatment rules is shown to provide little more than semantic explication of the chosen definitions of key terms; in no way can such explication serve as a substitute for empirical research on psychotherapy effects.     

Humean supervenience and best-system laws

David Lewis has proposed an analysis of lawhood in terms of membership of a system of regularities optimizing simplicity and strength in information content. This article studies his proposal against the broader background of the project of Humean supervenience. In particular, I claim that, in Lewis's account of lawhood, his intuition about small deviations from a given law in nearby worlds (in order to avoid backtracking and epiphenomena) leads to the conclusion that laws do not support (certain) counterfactuals and do not bestow nomic necessity on (certain) facts induced by these laws. Support of counterfactuals and nomic necessity, however, are widely held to be important aspects of the concept of lawhood. In my view, therefore, it is not possible to abandon these criteria in any satisfactory analysis of the notion of laws of nature. In a final section, I suggest that the whole project of Humean supervenience is misleading. It does not sufficiently take notice of the important role that reasoning about contrary-to-fact situations plays in modern scientific practice.     

Idealization in Applied First-Order Logic

Applying first-order logic to derive the consequences of laws that are only approximately true of empirical phenomena involves idealization of a kind that is akin to applying arithmetic to calculate the area of a rectangular surface from approximate measures of the lengths of its sides. Errors in the data, in the exactness of the lengths in one case and in the exactness of the laws in the other, are in some measure transmitted to the consequences deduced from them, and the aim of a theory of idealization is to describe this process. The present paper makes a start on this in the case of applied first-order logic, and relates it to Plato's picture of a world or model of 'appearances' in which laws are only approximately true, but which to some extent resembles an ideal world or model in which they are exactly true. This revised version was published online in June 2006 with corrections to the Cover Date.     

The logical status of natural laws

In this note I have presented the essentials of a view of how laws are falsified, a view which has been held by some notable philosophers but which is radically opposed to that of Professor Popper. I have not scrupled to ‘improve? upon it, so the view of no one philosopher is presented. I try to show that an interesting and convincing account of scientific simplicity is implicit in the theory and I conclude by suggesting how we can bring the argument to bear on the problem of the logical status of laws of nature, showing that through their manner of falsifiability, laws share some characteristics with necessary statements as well as with empirical generalizations.     

Realism and the underdetermination of theory

The main theme is that theorizing serves empirical prediction. This is used as the core of a counter to contemporary anti-realist arguments. Different versions of the thesis that data underdetermines theory are identified and it is shown that none which are acceptable differentiates between theory selection and prediction. Criteria sufficient for the former are included amongst those necessary for the latter; and obviously go beyond mere compatibility with data.Special attention is given to causal process theories. It is argued that the only empirically equivalent alternatives which can be constructed to any theory of this kind must be parasitic on that theory; so a choice for the original theory can not be avoided. Once this is established, a positive case for taking a realist position can be developed.     

Are the laws of physics ‘economical with the truth’?

It has been argued that the fundamental laws of physics are deceitful in that they give the impression of greater unity and coherence in our theories than is actually found to be the case. Causal stories and phenomenological relationships are claimed to provide a more acceptable account of the world, and only theoretical entities — not laws — are considered as perhaps corresponding to real features of the world.This paper examines these claims in the light of the author's own field of research: high energy physics. Some of the distinctions upon which the above conclusions are based are found not to be tenable in practice. Examples from experimental particle physics are presented which suggest an important role of the underlying theoretical structure which cannot be overlooked. It is argued that the fundamental theories must, in fact, be treated as being as worthy or unworthy of ontological commitment as the entities they postulate or the phenomenological relationships they inspire. Whilst it is conceded that aspects of the current theoretical formalism belie literal interpretation, it is maintained that revision in these particular areas need not affect the symmetry principles, particle spectra, or coupling strengths that largely determine the empirical content of the theory.Various other reasons for believing that the laws of physics may be dishonest are examined and in particular attention is drawn to the current tendency in particle physics to judge a theory's merits by aesthetic criteria. The difficulty of providing a sound justification for this behaviour does lead to the suspicion that our abstract representation of the world may in fact be coloured by anthropomorphic prejudices. The question then remains as to whether this merely points to a certain embellishment of the truth or the masquerading of a lie.I would like to thank my colleagues in high energy physics for their comments on this paper, and I am also particularly indebted to members of the Department of History and Philosophy of Science at Cambridge University for many fruitful discussions on these and related topics. I have benefitted over many years from stimulating philosophical arguments with my friend Alan Birchall, of the NRPB. I would like to dedicate this paper to the memory of John Bell, who had arranged to meet with me at CERN to discuss some of these topics shortly before his tragic death. He was an inspiration to many of us in high energy physics, with interests in the wider issues raised by our subject, and he will be greatly missed.     

Science, metaphysics and method

While there are many examples of metaphysical theorising being heuristically and intellectually important in the progress of scientific knowledge, many people wonder how metaphysics not closely informed and inspired by empirical science could lead to rival or even supplementary knowledge about the world. This paper assesses the merits of a popular defence of the a priori methodology of metaphysics that goes as follows. The first task of the metaphysician, like the scientist, is to construct a hypothesis that accounts for the phenomena in question. It is then argued that among the possible metaphysical theories, the empirical evidence underdetermines the right one, just as the empirical evidence underdetermines the right scientific theory. In the latter case it is widely agreed that we must break the underdetermination by appeal to theoretical virtues, and this is just what should be and largely is done in metaphysics. This is part of a more general line of argument that defends metaphysics on the basis of its alleged continuity with highly theoretical science. In what follows metaphysics and theoretical science are compared in order to see whether the above style of defence of a priori metaphysics is successful.     

Two types of empirical adequacy: a partial structures approach

The notion of empirical adequacy has received recent philosophical attention, especially within the framework of the semantic approach. Empirical adequacy, as explicated in the semantic approach, concerns the relationship between empirical substructures and some phenomena. The aim here is to differentiate this notion of empirical adequacy from one concerning the relationship between data and phenomena. Distinguishing each notion of empirical adequacy emphasizes different aspects of scientific practice—one concerning theory-development from the basis of an established theory, the other concerning theory-development from the basis of data-fitting, where established theory may not foster further development. To illustrate this contrast, an example from financial economics is considered.     

论自然律与因果知识的知觉经验基础

<正>一、引论自休谟以来,特别是在科学哲学的演进中,自然律理论与因果理论从来是不可分离的。相比而言,自然律理论具有某种优先地位。因为按照休谟的广为接受的论证,人类的知觉经验并不能直接辩     

Essentialism and the Necessity of the Laws of Nature

In this paper I discuss and evaluate different arguments for the view that the laws of nature are metaphysically necessary. I conclude that essentialist arguments from the nature of natural kinds fail to establish that essences are ontologically more basic than laws, and fail to offer an a priori argument for the necessity of all causal laws. Similar considerations carry across to the argument from the dispositionalist view of properties, which may end up placing unreasonable constraints on property identity across possible worlds. None of my arguments preclude the possibility that the laws may turn out to be metaphysically necessary after all, but I argue that this can only be established by a posteriori scientific investigation. I therefore argue for what may seem to be a surprising conclusion: that a fundamental metaphysical question – the modal status of laws of nature – depends on empirical facts rather than purely on a priori reasoning.     

Malthus's Essay on Population: the facts of "super-growth" and the rhetoric of scientific persuasion

For the Malthusian theory of population to be accepted as "scientific," it was essential that the theory be established on wide empirical evidence. A close examination of the "facts" provided by Malthus, however, shows that many of his crucial facts are based on distortions of the available evidence. Malthus was probably aware of much of this weakness, but for rhetorical reasons he persisted with the sandy empirical foundations from which he began.     

Capacities,explanation and the possibility of disunity

Nancy Cartwright argues that so-called capacities, not universal laws of nature, best explain the often complex way events actually unfold. On this view, science would represent a world that is fundamentally "dappled", or disunified, and not, as orthodoxy would perhaps have it, a world unified by universal laws of nature. I argue, first, that the problem Cartwright raises for laws of nature seems to arise for capacities too, so why reject laws of nature? Second, that in so far as there is a problem, it concerns the role of counterfactuals in explanation; I then briefly propose a simple model of counterfactual explanation. Finally, I investigate how a sophisticated version of the regularity theory of laws of nature (that of Ramsey-Lewis) can be neutral between the empirical hypotheses that the world is unified, and that the world is disunified.     

Continuity of Theory Structure: A Conceptual Spaces Approach

By understanding laws of nature as geometrical rather than linguistic entities, this paper addresses how to describe theory structures and how to evaluate their continuity. Relying on conceptual spaces as a modelling tool, we focus on the conceptual framework an empirical theory presupposes, thus obtain a geometrical representation of a theory’s structure. We stress the relevance of measurement procedures in separating conceptual from empirical structures. This lets our understanding of scientific laws come closer to scientific practice, and avoids a widely recognised deficit in current philosophy of science accounts, namely to risk a collapse of the physical into the mathematical.     

Preference-based belief revision for rule-based agents

Agents which perform inferences on the basis of unreliable information need an ability to revise their beliefs if they discover an inconsistency. Such a belief revision algorithm ideally should be rational, should respect any preference ordering over the agent’s beliefs (removing less preferred beliefs where possible) and should be fast. However, while standard approaches to rational belief revision for classical reasoners allow preferences to be taken into account, they typically have quite high complexity. In this paper, we consider belief revision for agents which reason in a simpler logic than full first-order logic, namely rule-based reasoners. We show that it is possible to define a contraction operation for rule-based reasoners, which we call McAllester contraction, which satisfies all the basic Alchourrón, Gärdenfors and Makinson (AGM) postulates for contraction (apart from the recovery postulate) and at the same time can be computed in polynomial time. We prove a representation theorem for McAllester contraction with respect to the basic AGM postulates (minus recovery), and two additional postulates. We then show that our contraction operation removes a set of beliefs which is least preferred, with respect to a natural interpretation of preference. Finally, we show how McAllester contraction can be used to define a revision operation which is also polynomial time, and prove a representation theorem for the revision operation.     

The Emergence of Better Best System Laws

The better best system account, short BBSA, is a variation on Lewis’s theory of laws. The difference to the latter is that the BBSA suggests that best system analyses can be executed for any fixed set of properties (instead of perfectly natural properties only). This affords the possibility to launch system analyses separately for the set of biological properties yielding the set of biological laws, chemical properties yielding chemical laws, and so on for the other special sciences. As such, the BBSA remains silent about possible interrelations between these freestanding sets of laws. In this paper, I explicate an emergence relation between them which preserves the autonomy or novelty of each special science’s laws but also shows their dependence: the autonomy of each level’s generalisations is given because nomicity is conferred to them system intrinsic, their dependence is established via their supervenience on lower level laws. As will be shown, the autonomy of special science laws is further strengthened by their ceteris paribus character.     

Some comments on Lehrer semantics

Lehrer Semantics, as it was devised by Adrienne and Keith Lehrer, is imbedded in a comprehensive web of thought and observations of language use and development, communication, and social interaction, all these as empirical phenomena. Rather than for a theory, I take it for a ??model?? of the kind which gives us guidance in how to organize linguistic and language-related phenomena. My comments on it are restricted to three aspects: In 2 I deal with the question of how Lehrerian sense can be empirically distinguished from Lehrerian reference as a precondition for the claim that sense relationships are in general more stable than reference relations. It seems that this very claim must already be presupposed for doing the respective empirical investigation. But in 3, I argue for the option to interpret the Lehrers?? concept of sense resp. sense vectors as intension concepts, by which move one may gain a generalized concept, so-to-say ??graded analyticity??, containing Carnapian strict analyticity for language systems as the extreme case of sense vectors with maximum value. Such graded sense may also be empirically investigated in the case of normal languages. In 4, I plead for my view that what the Lehrers take for communal languages are really collections of family-resembling idiolects of individual speakers and hypotheses of individual speakers about the idiolects of their fellow speakers. This move should free us from the fiction of, and sterile discussions about, the ??true?? meanings of words, but nevertheless keep normal language communication possible. As a concluding remark I propose in 5 to have both: normal languages from an empirical point of view, and codified languages from a logical reconstructionist one.