I. Metaphysical naturalism and scientific realism
Methodological naturalism – that is, the assumption, for the ends of scientific investigation, that explanations of physical phenomena are only acceptable when they postulate 'natural' causes - is a generally accepted element of the scientific method. There is, of course, no particular requirement that a scientific theory should not have recourse to ‘supernatural’ evidence; even so, the criteria of observation, prediction, and experimentation leading to reproducible results are not congenial to the introduction of such evidence. Indeed, the very success of the scientific method, and the concomitant paucity of evidence for any supernatural phenomena, is seen by some as providing strong evidence for metaphysical naturalism – the thesis that the arrangement of matter and energy in spacetime exhausts ‘what there is’. Nonetheless, metaphysical naturalism is not as easily defended as some of its more vocal contemporary supporters might wish to believe.
Scientific theories do not, in general, make metaphysical claims; a given scientist can conform to methodological naturalism in the exercise of her discipline (in the generation and testing of hypotheses) while remaining entirely agnostic concerning the corresponding metaphysical view. While - once again - the scientific method in no way requires that she should, it is common for the scientific practitioner to proceed as if the physical world were both real and mind-independent; this corresponds largely to the naïve or commonsense (pre-Humean) view of the objective reality of the physical world in which many of the practical or technological aspects of science have their origins. To take the well-known puzzle: If a tree falls in the forest and there is no-one to hear it, the naïve proto-scientific view is that the ‘physical nature’ of its fall is such that, if there were an observer present, the observer would hear it. This, of course, is where what we might call the 'proto-scientific' and the 'proto-philosophical' accounts diverge. While a proto-philosophical account would depart from the phenomenal experience – from the event as ‘sound’ – the proto-scientific account postulates that, as a kind of physical event, the fall of any tree has the same general characteristics (including the characteristic of displacing a certain quantity of air). The account is completed by suggesting an elementary causal relation: the supplementary proto-law that, given the right conditions, any such event would be audible.
Insofar as they correspond to a first level of 'theoretical speculation' about the relations obtaining between observable phenomena and the observation sentences used to describe them, these are ‘proto-refinements’ of our naïve or pre-theoretical intuitions; I shall return later to a more sophisticated account of the process of refinement itself. Suffice it to say for the present that the proto-scientific account allows for the metaphysical theses that the physical world is real and mind-independent by suggesting that certain conditions obtain whether or not they are observed (or even, by extension, observable). While a philosophically-refined account of the proto-scientific view would undoubtedly point out that ‘allowing for’ is not ‘showing that’, the scientifically-refined account simply evacuates further metaphysical speculation (thus, scientifically-refined accounts are sometimes philosophically naïve). The proto-philosophical view is more sophisticated in that it departs from the given of the phenomenon – the experience of 'a sound'. Such a view has already questioned the naïve realism of the proto-scientific view: whatever the physical characteristic of the falling of some tree, if there is no-one to hear it, there is no experience of 'sound'. While the proto-scientific view postulates regularities in the world, all that we effectively know about these regularities is that they correspond to certain sequences of phenomenal experience. Thus, while it is the case that the falling of a tree makes a sound in the presence of a (human) observer, we are unable to affirm that it effectively 'makes a sound' when there is no human observer.
So, in a certain sense, metaphysical naturalism might seem philosophically naïve, as it departs from the view that the physical universe is effectively real and mind-independent. In philosophical terms, it gives precedence to what we experience over the way in which we experience it; it differs from naïve realism in postulating that the phenomena we experience are determined not by the object of perception itself but by the more general 'causal structure' of the physical universe - of which we are also a part (indeed, much of its sophistication is borrowed from scientific refinements of naturalism; this finds its full expression in the thesis that our perceptual apparatus has developed in response to the physical characteristics of our environment). Now, while it would be philosophically naïve to accept it too hastily, the view that the physical universe is effectively real and mind-independent is commonsensical enough, insofar as it conforms to certain of our most basic pre-theoretical intuitions. Of itself, the view doesn’t preclude dualism, and is even compatible with certain supernaturalist accounts. Metaphysical naturalism, however, draws from this 'reasonable' or ‘commonsensical’ view the entirely more substantial metaphysical conclusion that only the physical world has objective reality, and that non-physical phenomena can either be reduced to physical phenomena, or simply eliminated from our account.
Scientific realism – or scientism ?
Naïve acceptance of supernaturalism within a philosophical position does not seem intellectually viable for those of us who have no pre-theoretical reasons for accepting supernaturalism (and, at this point, I would underline that there are NO arguments for supernaturalism which are convincing to one who is not already predisposed to a supernaturalist account). Yet the naturalist’s appeal to, and faith in, the theories and findings of contemporary science might seem - to one holding the opposing view - equally naïve.
A number of naturalists – and many of those most present in the popular eye – are scientific realists. Yet scientific realism, like supernaturalism, has various forms. Generally speaking, the scientific realist can hold either that scientific theories are largely true (the semantic commitment); that we have reason to believe them, or a significant part of them (the epistemological commitment); or that they describe objective, mind-independent aspects of reality (the metaphysical commitment). How these commitments are organised, and what priority relations obtain between them, depends largely on the individual commentator; for present purposes we are more concerned with metaphysical commitment. A strong metaphysical commitment would, for example, hold that the hypothetical entities of physical science have effective existence; such a view is largely open to the argument from ‘pessimistic induction’, to the problem of the underdetermination of theory by evidence, and to the objections formulated by instrumentalism and by ‘confirmation holism’ (unsurprisingly, the majority of objections depart from epistemic considerations); it is further weakened by the partial nature of scientific theory and by unreconciled incompatibilities between our best-candidate physical theories. Indeed, given the present state of scientific knowledge, strong metaphysical commitment to scientific realism is as great a leap of faith as is supernaturalism; as such, it would be reprehensibly scientistic.
The ‘neo-Quinean’ view is perhaps more acceptably modest: for the neo-Quinean, the adoption of metaphysical naturalism in philosophy reflects the adoption of methodological naturalism in the sciences; nonetheless, her approach is more concerned with the methods of scientific enquiry than with its immediate findings. As Smart has remarked, Quine held "that philosophy and science are continuous with one another"; this is not a matter of subordinating philosophy to science, but rather of aligning scientific and philosophical investigation, and particularly in matters of 'first philosophy'. Now, the methodology of scientific investigation is independent of any metaphysical commitment – science has little to say about what ‘exists’. The scientific investigator can thus proceed ‘as if’ naturalism were true while avoiding any deeper questions concerning the actual ontological status of the entities he postulates (indeed, his approach is compatible with an instrumentalist view). The naturalist philosopher, on the other hand, cannot so easily evacuate such questions, and particularly if her field is metaphysics; however, for the neo-Quinean, scientific naturalism is not an matter of scientific realism, but rather a 'working hypothesis' from which we can evaluate and investigate certain metaphysical puzzles.
I vaguely recall a previous experience by Haris involving 'knee-jerking' and hemlock as a prescription by Sidney? I may now feel what it's like to have a knee-jerk, or perhaps have one's knee jerked! This is why:
There is common vein (we may as well keep it natural..) through the extremely elegant text below David - the value of PREDICTABILITY. I recall Naturalism (Newtonian?) being consigned to this 'fate' as it were. Its value to and in Mathematics (supporting Pythagoras) is of course insurmountable and has progressed industrial and technological practise beautifully.
My view may be unpopular and I may earn that hemlock journey as did Socrates, but I feel Naturalist view in essence may have had its role to play in the scheme of things, i.e. expanding Man's (and Woman's) view of the universe and the possibilities that could be exploited. It's essence has perhaps now morphed into a seemingly wider, dare I say, perhaps super-natural (?) view of metaphysics and fractal chaos?
Natasha
I’ll still defend naturalism against supernaturalism - for the reasons of prediction I set out before, but also because supernaturalism is a get-out-of-jail-free-card (perhaps the original get-out-of-jail-free-card). This is not a problem of prediction, but of explanation – basically, we get to the point in a explanation where we say “and then a miracle occurs” (with thanks to Sid Harris)….
If we accept that there is a God (whatever we take it to be) that can intervene in the physical universe, and that God can effect changes by non-physical means (that is, by bending or breaking “natural laws”), then the project of explanation comes to a grinding halt… whatever we know about the world can be changed from one second to another for no physical reasons whatsoever simply because “God wills it so”.
Of course, there’s still the Church of Albert Einstein of the Latter-Day Spinozans…
Fractal chaos is perhaps difficult to predict, but remains deterministic: indeed, what is remarkable about chaos is not that it is random, but rather that seemingly ‘random’ (i.e. unforeseen) results can be produced by an entirely deterministic system.
And as for metaphysics – well, if we discount the New Age interpretation, and if we keep the PoMos in their place, contemporary metaphysics is one of the least ‘supernaturalist’ enterprises imaginable…
David
It's not that I am concerned with believing that God has no authority in the scheme of things and tradition has no place - but rather that Man (or Woman) believes that HE is the centre and purpose of all things. What I DO adore in naturalism however is the demand that statement is not automatically accepted as truth, divine or not, and that evidence needs to be assigned. This is exciting: personal responsibility is finally assigned, to a limit, when the burden of proof begins to get difficult...
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