Evidence for physicalism and the room for emergence

In document The chances of higher-level causation: an investigation into causal exclusion arguments (Page 104-110)

Chapter 2: Kim’s causal exclusion argument against non-reductivism

2.2 A summary of Kim’s exclusion argument

2.3.3 The empirical/inductive argument for closure Evidence for physicalism and the room for emergence

Transference of energy or momentum from the outside would change the distribution of energy or momentum inside the system by changing the amount of energy or momentum at the same time, but this is not required for redistribution to take place. Redistribution only requires the transference of energy and momentum inside the system from one region to another. This is an important point for the discussion of physical closure. If redistribution

could happen in a way that deviates from normal evolution but takes place without energy transfer into the system from the outside, we would have an interesting third case at hand that is in no contradiction with conservation laws.

There is good reason to liberalise the redistribution premise in a way that includes that latter possibility (see Gibb 2010). We had reason not to start with a physical theory of causation, therefore in our analyses and reformulation of the premises, where it is possible, we should rely on a more permissive, neutral theory of causation like the counterfactual theory or the powers theory. In case we accept that causes are difference-makers whatever relation realizes their capacity to make a difference the redistribution premise becomes compatible with redistribution without the transference of physical energy from the outside and maybe more than that:

REDISTRIBUTABILITY*: Redistribution of energy and momentum can be brought about without supplying energy or momentum.

Conservation laws put no restrictions on what could initiate redistributions of energy or momentum. If the amount of energy and momentum remains constant in a system conservation is not violated. The former is true even if the redistribution that takes place is not in line with the normal evolution of the physical system driven solely by basic physical laws. This is exactly the point where classical and modern emergentists alike found a gap in the physicalist/mechanist worldview exploitable for their purposes. The last great British emergentist, C. D. Broad in his discussion of mind-body interaction and the conservation of energy principle suggested the following:

“[facts concerning the conservation of energy] suggest that all the energy of our bodily actions comes out of and goes back into the physical world, and that minds

neither add energy to nor abstract it from the latter. What they do, if they do anything, is to determine that at a given moment so much energy shall change from the chemical form to the form of bodily movement; and they determine this, so far as we can see, without altering the total amount of energy in the physical world.” (Broad 1925:109)

So, conservativeness might require the exclusion of certain kinds of interventions into a physical system, but the road is still open for the emergentist to say that physical energy can be redistributed by non-physical difference-making causes in line with physical conservation laws. So far, so good, but this has further important consequences we should make explicit. The emergentist, to be able to accommodate interventions of non-basic level physical origins, should deny the exclusiveness of basic physical laws40. This does not require

the violation of any basic physical law. According to most emergentists, physical laws apply to all things but under certain circumstances, when certain base level conditions are satisfied, some further laws/forces also apply to them in concert with base level physical laws. This is called downwards or top-down causation by most proponents of such views. This is how Hendry (2010) explains the idea succinctly:

“…to say that some system exhibits downward causation is to make a counternomic claim about it — that its behaviour would be different were it determined only by the more basic laws governing the stuff of which it is made.” Hendry (2010a:185)

40 For a detailed discussion of the issue concerning the scope of physical and emergent laws in the context of

The view is consistent with the ubiquity of basic physical laws, but it assumes special laws that are activated only in the context of certain higher-level phenomena. In those special contexts the behaviour of physical particles is determined not only by basic physical laws, but by special higher-level laws as well. Therefore, their behaviour cannot be predicted based solely on basic physical laws.

„Under the ubiquity of physics, physical principles constrain the motions of particular systems though they may not fully determine them.” Hendry (2010b:217)

It is important to note that it doesn’t matter whether emergent special laws are expressions of conservative or non-conservative vital, mental or other energies. Either way they don’t change the amount of physical energy in the system, what they change is only its distribution. There is some reason to think that they would be conservative. As Papineau explains,

“…the nature of other fundamental forces provides inductive reason to suppose these sui generis forces will be conservative in their own right.” (Papineau 2001:30)

And historically, it is true that most of those who believed that there are non-physical energies believed them to be conservative. But conservativeness is not a difference-maker when it comes to the question of empirical backing for emergent laws. The decisive question is, how do we get to know about the existence of emergent laws? A passage from C. D. Broad combined with insights already on our table helps to formulate an answer. Below, he talks about emergent chemical powers:

„If the emergent theory of chemical compounds be true, a mathematical archangel, gifted with the further power of perceiving the microscopic structure of atoms as

easily as we can perceive hay-stacks, could no more predict the behaviour of silver or of chlorine or the properties of silver-chloride without having observed samples of those than we can at present.” (Broad 1925:71-72)

According to Broad, to be able to differentiate emergent from non-emergent properties first we should have access to the most precise descriptions of basic level goings on, the exact microscopic physical structure of atoms and the basic-level ubiquitous laws that apply to them. In case the behaviour of chemical compounds cannot be derived from this information then we are faced with an instance of an emergent law. The source of our failure of derivation cannot be rooted in practical limitations, only if the derivation is impossible even for, as Broad (1925:70) formulates this, a mathematical archangel who has limitless computational powers can we conclude that we have empirical evidence for the existence of an emergent law. Using Hendry’s counternomic formulation, we can also say: in such a case, the calculated behaviour of a system governed only by basic physical laws would be different from its actual behaviour. The deviation from the results gained by the purely basic level ideal calculation could be assigned to the governing force of an emergent law.

We should highlight an important difference compared to basic physical laws. Empirical evidence for the existence of emergent laws can only be gathered under those special circumstances where they apply as their scope is limited to the special phenomena to which they apply. If such a form of emergentism were true, the behaviour of special systems like chemical systems would be calculable from the joint work of basic physical and emergent laws according to some rule of composition (See: McLaughlin 1992:31). Emergentism, conceptualised this way, is consistent with conservation laws and does not involve violations of basic physical laws.

But is it compatible with the causal closure of the physical? It is clearly not, but the contradicting premise as Papineau (2001:30) and Gibb (2010:379) both point out, is not the conservation premise in the argument for closure, as people might expect. It is the no energy premise. If there is no non-physical energy or in other worlds there are no non-physical forces, then there is nothing that could do the work of redistributing physical energy or momentum in a manner that deviates from the normal evolution of the system solely determined by basic physical laws. According to emergentists following the footsteps of Broad, a special science law would be a description of a physical energy redistribution pattern that cannot be accounted for solely in terms of basic physical laws but, as we already saw, can be explained using basic laws combined with emergent laws in accordance with certain rules of composition allowing the computation of what happens when something is acted upon by both basic and emergent laws.

According to Papineau, the no energy premise is based on positive inductive evidence from putative cases of successful reduction and on negative inductive evidence from physiology/biology. Obviously, the evidence for it is not fully conclusive, but if one accepts no energy as a starting point it excludes the possibility of emergent laws and also the possibility of redistribution not caused by energy or momentum transfer form without the local physical system under investigation.

According to some emergentists, like Hendry (2010a, 2010b), the empirical evidence is not fully convincing, especially when it comes to the classical example of the reduction of chemistry to quantum physics. In his classic article McLaughlin (1992) argues that even though emergentism is a coherent belief system, the reason why it went out of fashion after the 1920s is the development of quantum chemistry. As I briefly mentioned, for Broad and for most former emergentists like John Stuart Mill, chemistry provided a convincing case where

special science phenomena seemed to go beyond what physics could explain. In McLaughlin’s reconstruction, this new success in the reductive unification of the natural sciences brought about convincing new evidence for physicalism and at the same time against emergentism.

However, this presupposes that Broad’s mathematical archangel has done her job and relying on the Schrödinger equation calculated chemical behaviour based solely on lower- level information about physical particles below the chemical level of composition. Hendry (2010a) shows in persuasive manner that this is definitely not so. Even though the reduction of simple atoms was done in an acceptable way, the only clear case being the case of the hydrogen atom, the symmetry properties of even the simplest of molecules evade straightforward reduction. Existing “reductive” models simply put those properties “in by hand” (Hendry 2010a:185). The so-called Born-Oppenheimer approximation that scientists use to derive features of molecules “makes only a small difference to the calculated energy of the molecule, but it makes a big difference to its symmetry properties” (Hendry 2010a:185), therefore a significant addition is required to achieve the expected results. As symmetry properties are crucial to recover important chemical capacities and are only available on the chemical level this practice cannot be called a real, satisfactory approximation or reduction. The physicalist might wait for further theoretical developments on meta-inductive grounds, but the present state of affairs provides less support for unificationist optimism then usually claimed. Therefore, Hendry (2010a, 2017) declares a stalemate in the debate between the reductionist and emergentist sides.

In document The chances of higher-level causation: an investigation into causal exclusion arguments (Page 104-110)