Brian Skyrms' investigation of dynamic deliberation began when he contrasted dynamical deliberation based on evidential decision theory with dynamical deliberation based on causal decision theory (Skyrms 1982). According to Skyrms, counter intuitive features of deliberation dynamics based on evidential decision theory undercut attempts by Ellery Eells and Richard Jeffrey to use dynamical considerations to argue that evidential decision theory could be trusted to agree with the recommendations of causal decision theory in the examples that had been used to motivate causal decision theory.

The notion of a genetic program, as described by Mayr, is ripe for an analysis inspired, at least in part, by recent debates in the philosophy of science taken under the heading of realism versus anti-realism.

Brian Skynns 's Dynamics of Rational Deliberation (1990) answers questions I have puzzled over for thirty years, and suggests fresh approaches to other questions. Here I want to explore an answer, in Skynns's dynamic terms, to an old question on my agenda concerning Humean (or Kantian, or pragmatic) probabilistic accounts of causal talk:

That there was some chance element to evolutionary change was clear even to Darwin (cf. Hodge 1987; also Hodge & Kohn 1986), but chance has assumed a more central role in evolutionary theory since the early decades of this century. It was certainly clear to theoreticians such as Dobzhansky, Wright and Fisher that an adequate evolutionary theory would have to take a stochastic form, though they disagreed as to the significance of chance in evolution (Gigerenzer et al., 1989, ch. 4; Turner 1987). As Beatty explains, the central difference is that in more modern treatments, not only is the origin of variations a matter of chance, their evolutionary fates are also matters of chance (Beatty 1984; cf. Beatty 1987). Probabilistic theories of evolutionary change, as we shall be concerned with them, emphasize this dependency of evolutionary fates on chance, and treat evolutionary change as irreducibly probabilistic.

The classical game theory ofvon Neumann and Morgenstern (1947) is built on the concept of equilibrium. I will begin this essay with two more or Jess controversial philosophical claims regarding that equilibrium concept:

1. (1) The explanatory significance of the equilibrium concept depends on the underlying dynamics.

2. (2) When the underlying dynamics is taken seriously, it becomes apparent that equilibrium is not the central explanatory concept.

What is relativistic quantum theory? How does it differ from non-relativistic quantum mechanics? Is there something more involved than the transition from the Galilean group to the Lorentz group?

These questions are evidently of great importance to the understanding of relativistic quantum theory (RQT), in particular to the distinction between the basic principles of quantum theory, and the characterization of a particular class of dynamical evolutions. Within non-relativistic quantum mechanics (NRQM) a reasonably precise response is possible (differences concern the number of degrees of freedom, the existence of internal symmetries, and the form of the Hamiltonian as a function of the canonical variables); what appears characteristic of RQT is the appearance of a dynamics of a qualitatively different character (involving the creation and annihilation of particles), involving new kinds of constraints (renormalization theory: anomalies). Nevertheless, it seems we must know how to pass from the inhomogeneous Galilean group (IHGG) to the Lorentz group (IHLG), if only because we have successfully constructed a RQT, surely, then, we know what it is that we hold invariant in this transition.

The term “experimental philosophy” has been used to refer to the solution of what were considered philosophical problems by means of laboratory experiments. A recent example of this was the experimental violation of the Bell inequality, which ruled out certain philosophically appealing “realist local” theories as alternatives to quantum mechanics (QM).

Following the spirit of such experimental philosophy, this paper proposes a feasible test between two different interpretations concerning the nature of “mixtures” in QM. The use of delayed coincidence techniques seems to show that the process of mixing beams of light in different polarizations is reversible, favoring a weak version of the so-called “ignorance interpretation” over the “instrumentalist” view.

Just what form(s) our cognitive attitudes towards scientific theories take, and what forms they should take, is a long-standing puzzle in philosophy of science. Debates continue, between various realist and anti-realist positions, probabilistic models, and others. The nature of cognitive commitment becomes particularly puzzling when scientists’ commitments are (at least apparently) inconsistent. Since there are no models of inconsistent sets of sentences, straightforward semantic accounts fail. And syntactic accounts based on classical logic also collapse, since the closure of any inconsistent set under classical logic includes every sentence.

Quantum field theory (QFT) poses the following well-known problem. Calculations of values for certain quantities begin with a first-order approximation to which are added higher order corrections. In many cases, the calculation of even the very first higher order correction term yields infinite values. These infinite values are due to divergences in the theory. These divergences can be traced to their source in the standard fundamental assumptions defining QFT. No matter which version of the formalism we adopt, we are trying to incorporate into the mathematics certain fundamental physical constraints on the nature of the vacuum state, on the states that can be occupied by systems, on the comeasurability of observables, and so on. The resulting formalism contains divergences.

In traditional philosophy of science, we routinely attribute powers to scientists that are near divine. It is only in desperate circumstances that we may even entertain the possibility that scientists are not logically omniscient and do not immediately see all the logical consequences of their commitments. The inhabitants of the grubby world of real science fall far short of this ideal. In truth they will routinely commit themselves consciously and even enthusiastically to the great anathema of philosophers: a logically inconsistent set of propositions.

Suppose we set about creating pairs of photons in the singlet state, allow them to separate to some considerable distance, and then send each photon into a polarizer oriented at some randomly chosen angle. Quantum theory predicts that in the long run we will observe the following behavior. On each wing of the experiment we will see perfectly random behavior. Roughly half of the photons will pass their polarizers and half will be absorbed. There will be no correlation between passage or absorption in one experiment and passage or absorption in the succeeding experiments. There will be no correlation between the passage or absorption and the angle at which the polarizer is set. But when we examine the correlations between the two wings of the experiment, something remarkable emerges.

Paraconsistent logic is one of those areas of philosophical logic that has yet to find much in the way of acceptance from a wider audience. By this I mean even a wider audience of philosophical logicians, let alone others. The area remains, in a word, disreputable. For some this is a positive attraction but, for the most part, it has kept away those in need of the services of a paraconsistent account of reasoning, in droves. In this brief essay, I try to reassure potential consumers that it is not in fact necessary to become a radical in order to use paraconsistent logic.

A common metaphor compares mathematics to a building: The axioms are its foundation, the lemmas and theorems and corollaries are its stones and bricks, logical deduction is the mortar or cement that holds them together. Once it is agreed, as it came to be in the nineteenth century, that mathematics is to be organized as a deductive science, with new results logically deduced from old, and ultimately from axioms, certain questions, not themselves straightforwardly mathematical, about the choice and status of the axioms to be adopted then arise. These are metaphorically called “foundational” questions by philosophers.

Convergent realists typically maintain the following theses:

1. Tl: Some scientific theories, literally interpreted, are at least approximately true.

2. T2: Some scientific theories, literally interpreted, genuinely refer.

3. T3: The history of mature sciences is a progressive approximation to the truth.

4. T4: The world (reality) described by scientific theories is independent of our thoughts or theoretical commitments.

Convergent realists usually offer the infamous “success of science” argument as the strongest defense of their view. Scientific realism, according to convergent realists, is the only view that does not portray the success of science as miraculous (i.e., unexplainable). Various versions of convergent realism have been defended by writers such as Richard Boyd (1973,1980,1984), W.H. Newton-Smith (1978), Hilary Putnam (1975,1978), JJ.C. Smart (1963,1985,1989), and Russell Hardin and Jay Rosenberg (1982). Critics of convergent realism include Larry Laudan (1981), Arthur Fine (1984), and Bas van Fraassen (1980).

Does science justify any part of mathematics and, if so, what part? These questions are related to the so-called indispensability arguments propounded, among others, by Quine and Putnam. The general idea of the arguments has been fonnulated (for critical assessment) by Penelope Maddy in a recent article as follows:

An effective way to challenge scientific realism these days is to ask whether evidence for a theory’s truth can ever outstrip evidence for its utility. Granted that we might have strong evidence of a theory’s explanatory, predictive, heuristic, and technological utility, might we have in addition evidence of its truth? A negative answer claims that all the evidence in support of a theory is, immediately, evidence of pragmatic virtues, and only indirectly, if at all, evidence of truth. Realism then reduces to a willingness to infer truth from utility. Evidently, none of the evidence by which theories are tested will pertain to this inference, so the only recourse for sustaining it is to a metalevel at which truth and utility are compared in the abstract. And there enormous problems loom.

One nice thing about the title of this symposium is the ease of finding a one-word answer. A disadvantage, however, is that “science” is ambiguous: is “philosophy of mathematics” included in “philosophy of science” or not? If so, the one-word answer is obviously obvious; but if not, the same answer is still pretty obvious, or so I hope it will appear by the end of this symposium. In fact, I believe that recent work in foundations of mathematics, especially of the sort represented in this symposium, serves to sharpen considerably central debates in both philosophy of mathematics and philosophy of science generally, especially on the question of realism (vs. instrumentalism, or varieties of constructivism, or nominalism), and on the question of the indispensability of highly theoretical concepts and axioms for the more observational portions of mathematics and science.

The central theme of this paper is that historical contingency plays an essential and ineliminable role in the construction and selection of a successful scientific theory from among its observationally equivalent and unrefuted competitors. Let me make a few clarifying remarks at the outset. It is not my claim that in all cases of theory selection there is in practice this radical type of underdetermination. Nor am I concerned with the rather trivial and philosophically uninteresting historical contingency of who did what when. For example, in response to Napoléon’s fishing for a favorable comparison between himself and Newton, Lagrange is said to have lamented (Gillispie 1960, p. 117; Moritz 1914, p. 167): “Newton was the greatest genius that ever existed, and the most fortunate, for we cannot find more than once a system of the world established.“

This symposium was sparked by a rather sad editorial by Larry Laudan in the twentyyear issue of Studies in History and Philosophy of Science. Laudan, one of the founders of that joumal, was weeping at the decline of the wonderful post-Kuhnian Spring of the late 1960s into the arid “social constructivist” autumn of the late 1980s. When once it had seemed that philosophers and historians of science would walk forward together, sweeping aside the ahistoricism of neo-positivists and the whiggishness of traditional history of science (generally written by retired scientists), now philosophers go alone while historians have been seduced by the fruity charms of the relativists and sociologists.

If the appropriate cognitive model of the mind is a connectionist model, then what does the future of folk psychology (FP) look like? “Bleak” say the eliminative materialists. In several recent articles and books Paul and Patricia Churchland have been arguing by demonstration that there are models on which to explain all behavior—not merely cognitive behavior—models which are more fruitful than FP. These models, which are connectionist in nature, are supposed to describe a better theory of behavior than FP, and so will eventually replace it. In this paper I look at several arguments the Churchlands have advanced for the thesis that FP will be replaced in a mature cognitive science, i.e., that connectionism will supplant FP.