Bas C. Van Fraassen

There are a number of dimensions to the realism-nominalism controversy. The topics of debate comprise: necessary connections and causality, dispositions and counterfactuals, space and time, the existence of abstract entities and mathematical objects, the existence of the theoretical entities of science. On all these except the last, Sellars takes a non-realist line: and on all these except the last, I agree with him to the extent that I presently have an opinion on them. But Sellars is a scientific realist, encapsulating this realism in the dictum: “to have good reason for holding a theory is ipso facto to have good reason for holding that the entities postulated by the theory exist”.

In response to parts I-III of G Rosen's "What is Constructive Empiricism?", "Philosophical Studies", 74, 1994, 143-178, this paper examines several construals of the position of constructive empiricism. At issue, in part, is the equation of intentional aspects of science with the intentions and opinions of scientists. In addition it is necessary to distinguish the constructive empiricist -- a philosopher holding that acceptance of theories in science need not involve belief that they are true -- from the scientific agnostic' who accepts but does not believe current science. What is at stake for empiricism is a view of science that will admit it as a paradigm for rational inquiry

The question of David Armstrong's recent book, What Is a Law of Nature? would seem to have little point unless there really are laws of nature. However that may be, so much philosoFhical thinking has utilized this concept, that an inquiry of this sort was needed whether there are or not. The book begins with a devastating attack on so-called Regularity views of law, and then proceeds with an exposition of Armstrong's own answer to the question. I wish to raise here some difficulties for Armstrong's answer, concentrating on his account of probabilistic laws where I see the severest problems. To locate myself with respect to his approach, however, I shall first enter some lesser demurrals.

When the reader turns to a text, he conceives of the narrated events as ordered in time. When the natural philosopher turns to the world, he also conceives of its events as ordered in time—or lately, in space-time. But each has the task of constituting this order on the basis of clues present in what is to be ordered. Interrogating the parallels to be found in their problems and methods, I shall argue that in both cases the definiteness of the relation between the order and what is ordered resides mainly in how the matter is to be conceived, and is underdetermined by the facts.

In The Inference That Makes Science, Ernan McMullin recounts the clear historical progress he saw toward a vision of the sciences as conclusions reached rationally on the basis of empirical evidence. Distinctive of this vision was his view of science as driven by a specific form of inference, retroduction. To understand this properly, we need to disentangle the description of retroductive inference from the claims made on its behalf. To end I will suggest that the real rival to McMullin's vision of science is not the methodologies he criticizes so successfully but a more radical empiricist alternative in epistemology

What is empiricism? There can be no authoritative answer to any such question. A historian of philosophy can at best try to call what is common to philosophers who either identified themselves, or have traditionally been identified, as empiricists. But what has set those philosophers apart from others, and especially from those whom they criticized, may not be captured in common views or doctrines. The historian may, in trying to fix the label, rely tacitly on a view of what philosophical positions are and how they are to be identified. Finally, it is typical of philosophers who decide to range themselves under some pre-existing banner ("empiricism", "pragmatism", "phenomenology") to change the very philosophy they take on, as much as did their historical heroes in their day. I will here try to give a sustained argument about what empiricism cannot be, and then enter upon a tentative exploration of what it should be (taken to be).

Decades of debate about scientific realism notwithstanding, we find ourselves bemused by what different philosophers appear to think it is, exactly. Does it require any sort of belief in relation to scientific theories and, if so, what sort? Is it rather typified by a certain understanding of the rationality of such beliefs? In the following dialogue we explore these questions in hopes of clarifying some convictions about what scientific realism is, and what it could or should be. En route, we encounter some profoundly divergent conceptions of the nature of science and of philosophy.

In the philosophy of science, identity over time emerges as a central concern both as an ontological category in the interpretation of physical theories, and as an epistemological problem concerning the conditions of possibility of knowledge. In Reichenbach and subsequent writers on the problem of indistinguishable quantum particles we see the return of a contrast between Leibniz and Aquinas on the subject of individuation. The possibility of rejecting the principle of the identity of indiscernibles has certain logical difficulties, leading us inexorably from ontology into epistemology. For the epistemological problem we attend to the differences that emerged between the (neo-)Kantian and logical empiricist traditions, also saliently displayed in Reichenbach's writings. After examining the contrast between Kant's and Leibniz's conceptions of empirical knowledge, specifically with respect to the irreducibility of spatiotemporal determinations, we explore an application of a neo-Kantian view to the same problem of indistinguishable quantum particles.

Experimental modeling is the construction of theoretical models hand in hand with experimental activity. As explained in Section 1, experimental modeling starts with claims about phenomena that use abstract concepts, concepts whose conditions of realization are not yet specified; and it ends with a concrete model of the phenomenon, a model that can be tested against data. This paper argues that this process from abstract concepts to concrete models involves judgments of relevance, which are irreducibly normative. In Section 2, we show, on the basis of several case studies, how these judgments contribute to the determination of the conditions of realization of the abstract concepts and, at the same time, of the quantities that characterize the phenomenon under study. Then, in Section 3, we compare this view on modeling with other approaches that also have acknowledged the role of relevance judgments in science. To conclude, in Section 4, we discuss the possibility of a plurality of relevance judgments and introduce a distinction between locally and generally relevant factors