Online research in philosophy

Many philosophers insist that the most plausible solution to the exclusion problem is to adopt the so-called ‘autonomy approach’, which denies either upward or downward causation between mental and physical properties. But the question of whether the autonomy approach is compatible with respectable theories of causation has seldom been discussed in the literature. This paper considers two influential theories of causation, the counterfactual account and the regularity account. I argue that neither the counterfactual theory nor the regularity theory can support the autonomy approach – while the counterfactual approach fails to block downward causation, the regularity approach is unable to refute upward causation.

Experimental investigation of mechanisms seems to make use of causal relations that cut across levels of composition. In bottom-up experiments, one intervenes on parts of a mechanism to observe the whole; in top-down experiments, one intervenes on the whole mechanism to observe certain parts of it. It is controversial whether such experiments really make use of interlevel causation, and indeed whether the idea of causation across levels is even conceptually coherent. Craver and Bechtel have suggested that interlevel causal claims can be analysed in a causal and a non-causal component. I accept this idea but argue that their account should be modified so as to account of cases of apparent downward causation. First, constitution must be distinguished from identity; second, the analysis of downward causation requires the concept of a partial constraint. An analysis along these lines shows that the possibility of downward causation is not refuted by Kim's argument according to which it is incompatible with the completeness of physics.

Recent developments in nonlinear dynamics have found wide application in many areas of science from physics to neuroscience. Nonlinear phenomena such as feedback loops, inter-level relations, wholes constraining and modifying the behavior of their parts, and memory effects are interesting candidates for emergence and downward causation. Rayleigh–Bénard convection is an example of a nonlinear system that, I suggest, yields important insights for metaphysics and philosophy of science. In this paper I propose convection as a model for downward causation in classical mechanics, far more robust and less speculative than the examples typically provided in the philosophy of mind literature. Although the physics of Rayleigh–Bénard convection is quite complicated, this model provides a much more realistic and concrete example for examining various assumptions and arguments found in emergence and philosophy of mind debates. After reviewing some key concepts of nonlinear dynamics, complex systems and the basic physics of Rayleigh–Bénard convection, I begin that examination here by (1) assessing a recently proposed definition for emergence and downward causation, (2) discussing some typical objections to downward causation and (3) comparing this model with Sperry’s examples.

The idea of a higher level phenomenon having a downward causal influence on a lower level process or entity has taken a variety of forms. In order to discuss the relation between emergence and downward causation, the specific variety of the thesis of downward causation (DC) must be identified. Based on some ontological theses about inter-level relations, types of causation and the possibility of reduction, three versions of DC are distinguished. Of these, the `Strong' form of DC is held to be in conflict with contemporary science; the `Medium' version of DC may for instance describe thoughts constraining neurophysiological states, while the `Weak' form of DC is physically acceptable but may not in practice be a feasible description of the mind/brain or the cell/molecule relation. All forms have their specific problems, but the Medium and the Weak version seems to be most promising.

The importance of downward causation lies in showing that it shows that functional properties such as mental properties are real, although they cannot be reduced to physical properties. Kim rejects nonreductive physicalism, which includes leading functionalism, by eliminating downward causation, and thereby returns to reductionism. In this paper, I make a distinction between two aspects of function—functional meaning and functional structure and argue that functional meaning cannot be reduced to the physical level whereas functional structure can. On this basis, I further distinguish between the integer of the function, which includes the functional meaning and the functional structure, and the whole of the functional realization, and also among the strong, medial, and weak supervenience relations. So-called downward causation is indeed the relationship between the whole of the functional realization and its physical realizer, which is a whole-part relation instead of a relation between levels. As a result of understanding downward causation in this way and abandoning the principle of the causal closure of the physical world, Kim’s argument becomes invalid and nonreductive functionalism, justified.

Weak emergence has been offered as an explication of the ubiquitous notion of emergence used in complexity science (Bedau 1997). After outlining the problem of emergence and comparing weak emergence with the two other main objectivist approaches to emergence, this paper explains a version of weak emergence and illustrates it with cellular automata. Then it explains the sort of downward causation and explanatory autonomy involved in weak emergence.

Several theories of emergence will be distinguished. In particular, these are synchronic, diachronic, and weak versions of emergence. While the weaker theories are compatible with property reductionism, synchronic emergentism and strong versions of diachronic emergentism are not. Synchronice mergentism is of particular interest for the discussion of downward causation. For such a theory, a system's property is taken to be emergent if it is irreducible, i.e., if it is not reductively explainable. Furthermore, we have to distinguish two different types of irreducibility with quite different consequences: If, on the one hand, a system's property is irreducible because of the irreducibility of the system's parts' behavior on which the property supervenes, we seem to have a case of "downward causation". This kind of downward causation does not violate the principle of the causal closure of the physical domain. If, on the other hand, a systemic property is irreducible because it is not exhaustively analyzable in terms of its causal role, downward causation is not implied. Rather, it is dubitable how unanalyzable properties might play any causal role at all. Thus, epiphenomenalism seems to be implied. The failure to keep apart the two kinds of irreducibility has muddled recent debate about the emergence of properties considerably.

The dominant position in Philosophy of Science contends that downward causation is an illusion. Instead, we argue that downward causation doesn’t introduce vicious circles either in physics or in biology. We also question the metaphysical claim that “physical facts fix all the facts.” Downward causation does not imply any contradiction if we reject the assumption of the completeness and the causal closure of the physical world that this assertion contains. We provide an argument for rejecting this assumption. Furthermore, this allows us to reconsider the concept of diachronic emergence.

The purpose of this paper is to lay bare the major problems underlying the concept of downward causation as discussed within the perspective of the present interest for phenomena that are characterized by self-organization. In our Discussion of the literature, we have focussed on two questions: (1) What sorts of things are said to be, respectively, causing and caused within the context of downward causation? And (2) What is the meaning of 'causing' in downward causation? We have concluded that the concept of 'downward causation' is muddled with regard to the meaning of causation and fuzzy with regard to the nature of the causes and the effects. Moreover, we have concluded that 'causation' in respect of 'downward causation' is usually understood in terms of explanation and determination rather than in terms of causation in the sense of 'bringing about'. Thus, the term 'downward causation' is badly chosen.