Online research in philosophy

Might the world be structured, as Leibniz thought, so that every part of matter is divided ad infinitum? The Physicist David Bohm accepted infinitely decomposable matter, and even Steven Weinberg, a staunch supporter of the idea that science is converging on a final theory, admits the possibility of an endless chain of ever more fundamental theories. However, if there is no fundamental level, physicalism, thought of as the view that everything is determined by fundamental phenomena and that all fundamental phenomena are physical, turns out false, for in such a world, there are no fundamental phenomena, and so fundamental phenomena determine nothing. While some take physicalism necessarily to posit a fundamental level, here I present a thesis of physicalism that allows for its truth even in an infinitely decomposable world.

Physicalism is usually understood as the claim that every empirical entity is or is determined by physical entities. The claim is however imprecise until it is clarified what are the physical entities in question. A sceptical argument in the form of a dilemma tries to show that this problem of formulation of physicalism cannot be adequately met. If we understand physical entities as the entities introduced by current physics, the resulting claim becomes most probably false. If we instead understand physical entities as those entities introduced by some future ideal physics, the claim then becomes indeterminate in content. Both horns seem equally bad. In the first part of the paper, I survey the strengths and weaknesses of different proposed solutions to this problem of formulation. In the second part, I lay out a new formulation of physicalism, partly based on a mereological principle, which overcomes the dilemma, and argue that it is a correct formulation of physicalism to the extent that it rules out clear antiphysicalist scenarios and is compatible with clear physicalist scenarios.

Dualism can be contrasted with monism, and also with physicalism. It is argued here that what is essential to physicalism is not just its denial of dualism, but the epistemological and ontological authority it gives to physical science. A physicalist view of the mind must be reductive in one or both of the following senses: it must identify mental phenomena with physical phenomena (ontological reduction) or it must give an explanation of mental phenomena in physical terms (explanatory or conceptual reduction). There is little reason to call a view which is not reductive in either of these senses “physicalism”. If reduction is rejected, then a non-physicalist form of monism is still available, which may be called “emergentism”.

Physicalism is the claim that that there is nothing in the world but the physical. Philosophers who defend physicalism have to confront a well-known dilemma, known as Hempel’s dilemma, concerning the definition of ‘the physical’: if ‘the physical’ is whatever current physics says there is, then physicalism is most probably false; but if ‘the physical’ is whatever the true theory of physics would say that there is, we have that physicalism is vacuous and runs the risk of becoming trivial. This article has two parts. The first, negative, part is devoted to developing a criticism of the so-called via negativa response to Hempel’s dilemma. In the second, more substantial, part, I propose to take the first horn of Hempel’s dilemma. However, I argue for a broad construal of ‘current physics’ and characterize ‘the physical’ accordingly. The virtues of the broad characterization of ‘the physical’ are: first, it makes physicalism less likely to be false; and second, it ties our understanding of ‘the physical’ to the reasons we have for believing in physicalism. That is, it fulfills the desideratum of construing our theses according to the reasons we have to believe in them.

Two ways are considered of formulating a version of retentive physicalism, the view that in some important sense everything is physical, even though there do exist properties, e.g. higher-level scientific ones, which cannot be type-identified with physical properties. The first way makes use of disjunction, but is rejected on the grounds that the results yield claims that are either false or insufficiently materialist. The second way, realisation physicalism, appeals to the correlative notions of a functional property and its realisation, and states, roughly, that any actual property whatsoever is either itself a physical property or else is, ultimately, realised by instances of physical properties. Realisation physicalism is distinctive since it makes no claims of identity whatsoever, and involves no appeal to the dubious concept of supervenience. After an attempt to formulate realisation physicalism more precisely, I explore a way in which, in principle, we could obtain evidence of its truth.

The distinction between token and type physicalism is a familiar feature of discussion of psychophysical relations. Token physicalism, or ontological physicalism, is the view that every token, or particular, in the spatiotemporal world is a physical particular. It is contrasted with type physicalism, or property physicalism -- the view that every first-order type, or property, instantiated in the spatiotemporal world is a physical property. Token physicalism is commonly viewed as a clear thesis, strictly weaker than property physicalism, strictly stronger than substance physicalism, and as a good statement on its own or in conjunction with other theses of minimal physicalism.[i] It is also generally simply assumed to be true, though Davidson has offered a famous argument for its truth, and some have argued against it. Many of those arguing against it are substance physicalists, indicating that they believe token physicalism to be a strictly stronger view.[ii].

Perhaps more controversial than whether physicalism is true is what exactly would have to be true for physicalism to be true. Everyone agrees that, intuitively at least, physicalism is the thesis that there is nothing over and above the physical. The disagreements arise in how to get beyond this intuitive formulation. Until about ten years ago, participants in this debate were concerned primarily with answering two questions. First, what is it for a property, kind, relation, or individual to be a physical one?

The debate over physicalism in philosophy of mind can be seen as concerning an inconsistent tetrad of theses: (1) if physicalism is true, a priori physicalism is true; (2) a priori physicalism is false; (3) if physicalism is false, epiphenomenalism is true; (4) epiphenomenalism is false. This paper argues that one may resolve the debate by distinguishing two conceptions of the physical: on the theory-based conception, it is plausible that (2) is true and (3) is false; on the object-based conception, it is plausible that (3) is true and (2) is false. The paper also defends and explores the version of physicalism that results from this strategy.

The debate over physicalism in philosophy of mind can be seen as concerning an inconsistent tetrad of theses: (1) if physicalism is true, a priori physicalism is true; (2) a priori physicalism is false; (3) if physicalism is false, epiphenomenalism is true; (4) epiphenomenalism is false. This paper argues that one may resolve the debate by distinguishing two conceptions of the physical: on the theory-based conception.