Modern mathematical sciences are hard to imagine without appeal to efficient computational algorithms. We address several conceptual problems arising from this interaction by outlining rival but complementary perspectives on mathematical tractability. More specifically, we articulate three alternative characterizations of the complexity hierarchy of mathematical problems that are themselves based on different understandings of computational constraints. These distinctions resolve the tension between epistemic contexts in which exact solutions can be found and the ones in which they cannot; however, contrary to a persistent myth, we conclude that having an exact solution is not generally more epistemologically beneficial than lacking one.

This article addresses the question of whether we should conceive of mechanisms as productive of change in a regular way. I argue that, if mechanisms are characterized as fully regular, on the one hand, then not enough processes will count as mechanisms for them to be interesting or useful. If no appeal to regularity is made at all in their characterization, on the other hand, then mechanisms can no longer be useful for grounding prediction and supporting intervention strategies. I conclude that, if the New Mechanistic Philosophy is to be successful, a stochastic characterization of mechanisms must be adopted.

Following an account of the incommensurability argument, an objection, based on assumptions concerning rival theories, is examined and rejected. This rejection leads to an alternative direction of criticism of incommensurability, a direction that involves the articulation of comparative standards of theory evaluation that are independent of meaning invariance.

This paper presents a critical examination of claims advanced by several philosophers to the effect that ‘time travel’ represents a physical possibility and that the interpretation of certain actually observed phenomena in terms of ‘time travel’ is both legitimate and advantageous. It is argued that (a) no convincing motivation for the introduction of the time travel hypothesis has been presented; (b) no coherent and interesting sense of ‘going backward in time’ has been supplied which makes ‘time travel’ compatible with Special Relativity; (c) even the conceptual possibility of ‘time travel’ is an unsettled and somewhat nebulous question.

Some ecologists have argued that theoretical model building in population and community ecology has gone evidentially unconstrained. In the essay, I argue that “bottle experiments” offer ecological model building evidential constraints and illustrate this by considering work on chaotic models tested by the dynamics of flour beetles. Critics reply that these experiments are importantly unlike nonmanipulated natural systems and thus do not constitute genuine tests of the models. I conclude by considering two responses to this worry and a suggestion on how to move forward on this debate.

In this article I argue that structure in chemistry is a creature of abstraction: attending selectively to structural similarities, we neglect differences. There are different ways to abstract, so abstraction is interest dependent. So is structure. First, there are two different and mutually irreducible notions of structure in chemistry: bond structure and geometrical structure. Second, structure is relative to scale (of energy, time, and length): the same substance has different structures at different scales, and relationships of structural sameness and difference vary across the scales. However, these facts have no tendency to undermine structure’s claim to reality, or its metaphysical seriousness.

Epistemic accounts of scientific collaboration usually assume that, one way or another, two heads really are more than twice better than one. We show that this hypothesis is unduly strong. We present a deliberately crude model with unfavorable hypotheses. We show that, even then, when the priority rule is applied, large differences in successfulness can emerge from small differences in efficiency, with sometimes increasing marginal returns. We emphasize that success is sensitive to the structure of competing communities. Our results suggest that purely epistemic explanations of the efficiency of collaborations are less plausible but have much more powerful socioepistemic versions.

Precaution is a relevant and much-invoked value in environmental risk analysis, as witnessed by the ongoing vivid discussion about the precautionary principle (PP). This article argues (i) against purely decision-theoretic explications of PP; (ii) that the construction, evaluation, and use of scientific models falls under the scope of PP; and (iii) that epistemic and decision-theoretic robustness are essential for precautionary policy making. These claims are elaborated and defended by means of case studies from climate science and conservation biology.

I consider and reject William Whewell's attack on the inductivism of Isaac Newton and John Stuart Mill, as well as John Norton's attack on any universal system of inductive rules. I also explain how a system of inductive rules of the sort proposed by Newton and Mill should be understood.

This article (i) uncovers a foundational relationship between the ‘gauge symmetry’ of a Newton-Cartan theory and the celebrated Trautman Recovery Theorem and (ii) explores its implications for recent philosophical work on Newton-Cartan gravitation.

Aldo Leopold’s land ethic, an extremely influential view in environmental ethics and conservation biology, is committed to the claim that interdependence between humans, other species, and abiotic entities plays a central role in our ethical responsibilities. Thus, a robust understanding of “interdependence” is necessary for evaluating the viability of the land ethic and related views, including ecological ones. I characterize and defend a Leopoldian concept of “interdependence,” arguing that it ought to include both negative and positive causal relations. I also show that strength and type of interdependence can vary with time, space, and context.

Comparativism—the view that mass ratios are not grounded in absolute masses—faces a challenge by Baker which suggests that absolute masses are empirically meaningful. Regularity comparativism uses a liberalized version of the Mill-Ramsey-Lewis Best Systems Account to have both the laws of Newtonian gravity and the absolute mass scale supervene on a comparativist Humean mosaic as a package deal. I discuss three objections to this view and conclude that it is untenable. The most severe problem is that once we have reduced away the absolute masses, there is nothing that stops us from also reducing the mass ratios.

This article analyzes the antireductionist argument from renormalization group explanations of universality and shows how it can be rebutted if one assumes that the explanation in question is captured by the counterfactual dependence account of explanation.

I develop a concept of observability that pertains to qualities rather than objects: A quality is observable if it can be registered by human sensation (possibly with the aid of instruments) without involving optional interpretations. This concept supports a better description of observations in science and everyday life than the object-based observability concepts presupposing causal information-transfer from the object to the observer. It also allows a rehabilitation of the traditional empiricist distinction between observations and their interpretations, but without a presumption that observations are infallible. Using this concept of observability, I also propose a re-formulation of constructive empiricism that is easier to defend against realist attacks, while open to reasonable realist intuitions.

The thermodynamics of computation assumes that computational processes at the molecular level can be brought arbitrarily close to thermodynamic reversibility and that thermodynamic entropy creation is unavoidable only in data erasure or the merging of computational paths, in accord with Landauer’s principle. The no-go result shows that fluctuations preclude completion of thermodynamically reversible processes. Completion can be achieved only by irreversible processes that create thermodynamic entropy in excess of the Landauer limit.

The proponents of the entrepreneurial university have claimed that it implies adjustments in the normative structure of science. In this article, I will critically examine whether a qualitatively new kind of academic ethos can emerge from the commercialization of academic research. The traditional conception of norms of science as institutionalized imperatives is distinguished from the constructivist conception of norms as strategic or ideological resources. An empirical case study on the commercialization of the research of one academic language-technology group is presented. The case study does not support the constructivist conclusion that the norms of science are malleable at will.

This paper examines Descartes' problematic relational theory of motion, especially when viewed within the context of his dynamics, the Cartesian natural laws. The work of various commentators on Cartesian motion is also surveyed, with particular emphasis placed upon the recent important texts of Garber and Des Chene. In contrast to the methodology of most previous interpretations, however, this essay employs a modern “spacetime” approach to the problem. By this means, the role of dynamics in Descartes' theory, which has often been neglected in favor of kinematic factors, is shown to be central to finding a solution to the puzzle of Cartesian motion.

In accepting the invitation of your society to discuss some aspects of the philosophy of science, particularly as they might bear on the problems of an experimental psychologist, I should like from the start to make it very clear that I do not consider myself a philosopher, not even an amateur one. Like most empirical scientists, particularly of the laboratory variety, I usually take it for granted that my world is real and that the things I perceive as existing in it can be investigated by my empirical methods. I seem to get along quite well with this unpremeditated, common-sense realism, and, for the most part, I go along minding my own experimental business. As the psychologists among you may know, however, every once in a while I seem to have to abandon this happy, naive state and let myself get involved in questions about my science, the kinds of questions that are more properly the business of the philosopher of science.

The world is beginning to look askance at Science. Or, rather, not beginning but intensifying an attitude of suspicion if not of downright hostility. We scientists are, of course, partly to blame; for we have so loudly proclaimed our virtues as the creators of radios and airplanes that, now these instruments are being abused as agents of mass propaganda and mass destruction, we are the obvious targets for the rising wrath of men. This is serious, for science is inseparably a part of the society and culture in which it is embedded, and it does not suffice to deny impatiently ourguilt and shrug away our responsibility to our fellows.