Where to Look for Emergent Properties

Abstract

Recent years have seen renewed interest in the emergence issue. The contemporary debate, in contrast with that of past times, has to do not so much with the mind–body problem as with the relationship between the physical and other domains; mostly with the biological domain. One of the main sources of this renewed interest is the study of complex and, in general, far-from-equilibrium self-preserving systems, which seem to fulfil one of the necessary conditions for an entity to be emergent; namely, that its causal powers are not predictable from the causal powers of basic physical properties. However, I argue that much of the current emergentism debate has misfired by focusing on the interpretation of self-maintaining systems. In contrast, I claim that if we want to find emergent properties, we should look not at complex systems, but at selection (natural selection, in particular). I argue that selection processes make the causal world ‘exuberant’ by making non-physical functional and relational properties enter the causal web of the world.

Acknowledgements

This article has benefited from discussions held in several seminars on emergence and downward causation organized by the IAS Research Group at the University of the Basque Country. I want to express my gratitude to Leonardo Bich, Arantza Etxeberria, Matteo Mossio, Alvaro Moreno, and particularly to Jon Umerez, who made a thorough reading of the draft and suggested improvements that I found very helpful. Thanks as well to the audience at the 6th SEFA Conference, in particular to Jordi Fernández. I also have to express my gratitude to two anonymous referees, who did a wonderful job providing comments that enabled me to improve the paper significantly and to correct several mistakes, as well as to the editor of ISPS, James McAllister. Finally, I want to thank Toffa Evans for the English revision. Research for this paper was funded by the Spanish Government, research projects FFI2010-15717 and FFI2011-30074-C02-02.

Notes

‘Downward causation’, a term introduced by Campbell (1974), refers to a causal relation between a higher-level property or system and a lower-level one.

This is because Kim is mostly interested in mental causation, where the issue is whether or not mental states can be said to produce either bodily movements or the physical states that subvene other mental states. Defenders of vertical downward causation, in contrast, focus on the relationship between wholes and their constituent parts.

Wilson (2010) makes a distinction between reducing, restricting and eliminating degrees of freedom. According to this distinction, what goes on in complex systems is not so much a reduction of degrees of freedom, but an elimination of them.

This radical empiricist attitude is best exemplified by Cartwright (1999). Cartwright argues that, given that we do not have any evidence that Newtonian physics can explain the fall of a dollar bill in the open air, we can doubt that Newtonian physics applies except in very controlled settings. By parity of reasoning, we could say that if there is no evidence for a physicalist explanation of complex systems, we had better believe that physicalist explanation does not account for complex systems. Dupré (2001) is another example of this ‘empiricist’ attitude.

I may be wrong in pointing out that Campbell's reflections on the role of natural selection somehow bring him close to my cause, and I do not want to suggest at all that the ‘orthodox’ interpretation of Campbell is defective. I am content with claiming that some of the points he makes are points I would endorse. Here is another interesting passage:From the point of view advocated here, these macrostructures [perhaps all of them understandable in terms of the science of microparticles] provide the raw material of variations on which biological natural selection can operate. They are, however, inadequate to predict or explain which variant organic forms will be most abundant. (Campbell 1990, 5)

As we lack a proper account of what it is for an entity to be physical, this is deemed to be controversial. From here on, I will assume that to be physical is to be a posit of physics, and that the functional and relational properties that I consider are not (and will not be) posits of physics. I think that it is possible to argue for this construal of the physical (Vicente 2011b). I also think that this is the notion of the physical involved in the physicalist/emergentist debate (or, at any rate, in the physicalist/emergentist debate as it concerns the present article). Other approaches, such as the ‘via negativa’ (Montero and Papineau 2005) or Crook and Gillett's (2001) account, tend to blur the terms of the debate, as biological properties (and the properties considered here) turn out to be physical (since ‘the physical’ is very broadly construed).

By this I only mean that selection processes have an effect on which properties have causal powers. A world without selection processes has fewer causally efficacious properties than one with selection processes. If we maintain, as many metaphysicians do, that ‘to be is to have causal powers’, then a world with selection processes is exuberant with respect to a world without them—a world with selection processes, for instance, has functional properties, while in a world without selection all that we find are functional concepts (on this distinction, see e.g. Kim 1998; Gillett 2003). I am aware that the slogan may be misleading in that it suggests that it is selection (not the processes that generate the variability on which selection operates) that is responsible for the manifest exuberance of the world. I am not claiming that at all. I hope this note serves to avoid such a misreading.

Functional properties are properties defined by their causal roles. Teleofunctional properties are properties defined by what they ought to do.

I have preferred not to talk about fitness because of the many problems associated with the notion (e.g. Rosenberg and Bouchard 2010). Depending on how fitness is understood, it may make no sense to hold that a being fitter than b has causal powers. Whereas it does make sense, I think, to claim that a having a better orientation sense than b, or a being weaker than b—which will be my toy example—have causal powers.

I am aware that speaking about future physics is problematic. Perhaps I could restrict the meaning of ‘the physical’ to that which is postulated by current physics and construe my claim as a claim indexed to the present time and physics. That is, my claim could be that, given current physics, properties such as being the weakest member of a herd are emergent properties. However, I suspect that this kind of predicate will not appear in the causal antecedent of any law of physics, current or future. One reason to think this is that physics already has explanations for the events that these properties explain—see below.

One can respond that the ultimate cause of the antelope's death is that the lion represented it as being the weakest of the herd, and that an explanation that appeals to this fact would not miss the information I have been talking about, while still being reducible to a physical explanation (the lion's representing the antelope as being so is, after all, a brain event). However, there is no need for the lion to represent the antelope as being the weakest member of the herd or to represent it as bearing any other kind of relation to the rest of the group. It can represent it just as being easy prey, or possible prey, or even not represent it at all—it may be that some anti-representational dynamical approach to lions' hunting is the correct one. That is, the correlation between instantiating the property of being the weakest of a herd and falling prey to a predator can be mediated by various mechanisms; and it is not necessary that part of the mediating mechanism is a detector of the weakest members of herds. So, my point stands: a physicalist-friendly explanation will plausibly miss some causal information, because (a) it will not invoke relational properties at any stage and (b) relational properties provide causal information. However, let me note one thing: I have chosen the example of the lion and the antelope for ease of exposition. If the fact that the lion is a representational device is judged to muddy the waters, the example could be substituted for one in which predators are not involved (see section 2 for some such examples).

To me, this means that determinables are indeed causally efficacious.

‘Weak’ is a gradable adjective that requires a comparison class and a standard. Suppose, for the time being, that one could talk about something such as ‘intrinsic weakness’.

Things are not nearly as clear in the case of functional properties such as being a blood pump and their role in selection processes. On the one hand, you cannot manipulate the functional properties of a particular, x, without manipulating its categorical properties: if you want to test whether, all things being equal, a non-blood-pumping heart does not endure, you have to alter its categorical properties. On the other hand, you can alter the categorical properties of a particular, x, without altering its functional properties, but only as long as the new categorical properties of x have the same causal powers as the old ones. That is, you cannot really test the causal powers of the categorical properties of x vis-à-vis its functional properties.