Online research in philosophy

In the first section of this paper, I articulate Jaegwon Kim's argument against emergent down ward causation. In the second section, I canvas four responses to Kim's argument and argue that each fails. In the third section, I show that emergent downward causation does not, contra Kim, entail overdetermination. I argue that supervenience of emergent upon base properties is not sufficient for nomological causal relationsbetween emergent and base properties. What sustains Kim's argument is rather the claim that emergent properties realized by base properties can have no causal powers distinct from those base properties. I argue that this is false.

This is one of two papers about emergence, reduction and supervenience. It expounds these notions and analyses the general relations between them. The companion paper analyses the situation in physics, especially limiting relations between physical theories. I shall take emergence as behaviour that is novel and robust relative to some comparison class. I shall take reduction as deduction using appropriate auxiliary definitions. And I shall take supervenience as a weakening of reduction, viz. to allow infinitely long definitions. The overall claim of this paper will be that emergence is logically independent both of reduction and of supervenience. In particular, one can have emergence with reduction, as well as without it; and emergence without supervenience, as well as with it. Of the subsidiary claims, the four main ones (each shared with some other authors) are: (i): I defend the traditional Nagelian conception of reduction (Section 3}); (ii): I deny that the multiple realizability argument causes trouble for reductions, or ``reductionism'' (Section 4); (iii): I stress the collapse of supervenience into deduction via Beth's theorem (Section 5.1); (iv): I adapt some examples already in the literature to show supervenience without emergence and vice versa (Section 5.2).

Rom Harré thinks that the Emergence–Reduction debate, conceived as a vertical problem, is partly ill posed. Even if he doesn’t wholly reject the traditional definition of an emergent property as a property of a collection but not of its components, his point is that this definition doesn’t exhaust all the dimensions of emergence. According to Harré there is another kind (or dimension) of emergence, which we may call—somewhat paradoxically—“horizontal emergence”: two properties of a substance are horizontally emergent relative to each other if they cannot be displayed in the same conditions. Contrary to vertical emergence, horizontal emergence is a symmetrical relation. Harré endorses horizontal emergentism. I argue that this position faces a principled difficulty: it makes it impossible to bind different horizontally emergent discourses in an interesting way. Physics and biology for example become “island” discourses, each speaking of a distinct kind of entities. The only way to ensure that two different discourses can relate to the same entity is to reintroduce verticality into the picture.

This paper examines the widespread intuition that the dynamical approach to cognitive science is importantly related to emergentism about the mind. The explanatory practices adopted by dynamical cognitive science rule out some conceptions of emergence; covering law explanations require a deducibility relationship between explanans and explanandum, whereas canonical theories of emergence require the absence of such deducibility. A response to this problem – one which would save the intuition that dynamics and emergence are related – is to reconstrue the concept of emergence as a relationship between laws. I call this “nomological emergence” and comment on the extent to which dynamicists would find it acceptable. Alternatively, dynamical cognitive science might be viewed as fitting better with the kind of “functional reductionism” which has recently been developed by authors such as Jaegwon Kim. Which of these two alternatives is preferable remains an open question pending the further development of dynamical cognitive science, particularly in its “non-classical” forms.

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.

Jaegwon Kim has argued (Kim 2006a) that the two key issues for emergentism are to give a positive characterization of the emergence relation and to explain the possibility of downward causation. This paper proposes an account of emergence which provides new answers to these two key issues. It is argued that an appropriate emergence relation is characterized by a notion of ‘transformation’, and that the real key issue for emergentism is located elsewhere than the places Kim identifies. The paper builds on Victor Caston’s important work on ancient philosophy of mind (Caston 1997, 2001), but appeals to sources he has not considered.