Chapter 1: Mental causation, multiple realization and physicalism
1.3 Physicalism and the physical determination of higher-level properties
1.3.2 The insufficiency of supervenience physicalism
First, as it has been argued by a number of philosophers (Crane 2001b, Kim 1999) it is not clear that supervenience physicalism can tell itself apart from emergentism, its most important traditional rival. Below, I will talk manly about an influential strand of emergentism that originates with C. D. Broad (1925). Emergentism, similarly to physicalism, is a form of substance monism, combined with property dualism. Emergent properties are both fundamental in the sense that they are not resultants, derivatives of physical properties, and dependent in the sense that they require certain underlying physical configurations for their emergence. They are also considered to be genuinely novel, in the sense that they have causal powers of their own not conferred by the underlying physical properties. These powers are expressed by emergent higher-level laws, so-called intra-ordinal laws. Emergent causal
powers exert so-called downward causal effects on physical properties. This view might sound weird for some, but there is a wider agreement today that it is a consistent view of nature (see e.g.: McLaughlin 1992, Hendry 2010b).
Emergent properties are connected to the physical base via synchronic trans-ordinal laws formally indistinguishable from a Nagelian bridge-law12. However, the metaphysical
content they express is different from mere connecting principles as the properties they connect to the physical base are not resultants of physical properties. This means that emergent properties supervene on the physical base, but the modal strength of the relation should be modified if one aims to grasp the content of emergentism in contrast to physicalism. For the emergentist trans-ordinal laws are fundamental laws much like the laws of physics. However, two possible worlds might differ with respect to trans-ordinal laws, without a difference in physical laws. So, according to the emergentist two worlds, identical in all fundamental physical respects, can differ with respect to their supervenient properties. To tell emergentism and physicalism apart philosophers introduced modifications into the modal strength of the supervenience relation, therefore strong supervenience usually comes in two flavours:
Metaphysical supervenience: NP supervenes on P in all metaphysically possible
Nomological supervenience: NP supervenes on P in all possible worlds governed
by the same laws as those governing the actual world (including trans-ordinal laws).
12 The view, especially in contemporary formulations, allows for both biconditional or one-way trans-ordinal
laws. This is also consistent with Nagelian formalisms. Interestingly, Nagel (1961) aknowledges that emergentism and reductionism can be captured by the very same formal descriptions.
Among others, Papineau (2008) believes that metaphysical supervenience expresses the commitments of physicalists, while nomological supervenience grasps the emergentist tenets. For emergentists, or even for full-blown dualists, it is possible that higher-level properties are absent from worlds were the required trans-ordinal laws are not in place. Contemporary dualists like Chalmers (1996) believe in the possibility of phenomenal zombies, beings that are identical to us in all physical respects but devoid of phenomenal mental states13. The same applies to any higher-level property an emergentist identifies as emergent,
like biological properties in the case of C. D. Broad (1925).
Jessica Wilson (2005) launched an influential attack against this distinction arguing that accepting the plausible view of dispositional essentialism, according to which physical properties are individuated by their causal powers and those causal powers are essential to the properties, one cannot make sense of having the same physical properties in a word with extra emergent causal powers and in a world without those. If physical properties are individuated by what they do, by their causal powers, then without emergent laws being replicated as well, it is impossible to instantiate the very same physical properties in a different world. According to this view, laws of nature express the causal powers and so properties are individuated by the laws of nature that apply to them. If there are laws over and above physical laws those emergent laws also express the causal powers of physical properties as emergent properties depend on configurations of physical properties. If Wilson
13 The problem of phenomenal consciousness is central to contemporary debates in the philosophy on mind.
There seems to be no way of explaining how phenomenal states can arise from physical states. On the one hand, phenomenal states are non-functional, so they resist the means of standard scientific methods, on the other hand, zombies physically identical to conscious humans, devoid of phenomenal conscious experience are at least conceivable (see: Chalmers 1996).
is right, then the nomological/metaphysical distinction cannot be used to differentiate physicalism from emergentism.
Fazekas (2014) has a notable counterargument to this line of thought. He objects that emergent laws don’t express the causal powers of the physical properties in the supervenience base of the relevant emergent property. This is because trans-ordinal laws are not causal laws, only higher-level, emergent intra-ordinal laws express causal powers and these causal powers are genuinely novel, fundamental powers by definition. They belong to emergent properties that are not resultants of the base properties. What is done by an emergent property is not done by the subvening physical properties. According to Fazekas, the reason why Wilson thinks that emergent laws express the causal powers of physical properties it that she, along with some important interpreters of emergentism like O'Connor & Wong (2015)14, fails to distinguish between emergent causal (intra-ordinal) and non-causal
(trans-ordinal) laws. A full-fledged dispositional essentialist might want to hold the view that a trans-ordinal law is just an expression of an essential potentiality that belongs to a subvening physical property, but that leaves no room for making sense of the emergentist claim according to which emergent properties instantiate genuinely novel causal powers in reality. If there are genuinely novel, emergent causal powers these cannot be essential potentialities of the physical base, because in that case they are not novel, not additions relative to the fundamental powers of physical entities. Therefore, such kind of essentialism would beg the question against the emergentist position.
14 The referenced O’Connor & Wong text is an influential SEP entry edited by them. In section 3.1. discussing the
„Standard Ontology of Emergence” describing mainly C.D. Broad’s version, they tell the reader: „newness of property, in this sense, entails new primitive causal powers, reflected in laws which connect complex physical structures to the emergent features. (Broad's trans-ordinal laws are laws of this sort.)” This recapitulation of the emergentist view overlooks the trans-ordinal vs. intra-ordinal distinction.
The question concerning the utility of different supervenience relations in defining physicalism is probably not settled yet, but assuming that Fazekas is right, strong metaphysical supervenience seems to be a satisfactory way to express the core, or as it is usually called, minimal commitment of physicalism. There are further worries concerning strong supervenience physicalism, but because the question is not central to my investigation in this thesis, I will set them aside here.