Resultados experimentales

Poland observes a distinction between what he calls a priori and a posteriori approaches to what he describes as ‘isolating the physical bases’, i.e. the task of saying what is to count as ‘physical’, where a posteriori approaches are those which rely upon ‘appeals to the empirical study of nature ... for grounds that distinguish the physical from the non-physical,’ while a priori methods depend upon ‘some form of conceptual or linguistic analysis or upon some other from of a priori argument purporting to provide definitive grounds for drawing the distinction between physical and non-physical...’ (1994: 112).16

Poland begins by rejecting some views, which in his terms are a priori, (including Rorty 1979: 20) which characterise the physical by specifying that it is the opposite of the mental. He objects that these views fail to give any significant positive content to physics, and are also hostage to the need to specify what is meant by mental to get off the ground. While there is something in these reservations, it is also worth bearing in mind that physicalists themselves have been prepared to concede, with Feigl (1958: 420), that the notion of ‘physical’ appears to be less clear than that of ‘mental’, which would lend some support to views which attempt to use the mental as a starting point.17

It could also be objected, perhaps more seriously, that such approaches concede too much at the outset to a paradigmatically seventeenth century way of distinguishing the mental and physical by opposing them, exemplified in Descartes’ account of unextended thinking substance, and unthinking extended substance. And to concede that is to concede too much to a broadly mechanist conception of matter as essentially inert,18 _{at the} very point where we are trying to ask what kind of thing physics is and what the physical is capable of.

Despite this, though, it is worth noting that from the perspective of the Completeness Thesis a negative characterisation may well turn out to play a useful role for the purposes of formulation and establishing what would count as evidence. As noted in the introduction to this thesis (section 1.1) Spurrett and Papineau (1999) argue that for the purposes of the standard type of argument for identity based on the rejection of

16 _{Poland’s choice of the terms a priori and a posteriori to divide the approaches he considers is somewhat} idiosyncratic, and it is far from clear that the approaches which he calls a priori are best thought as a priori in the typical contemporary senses of the term, even though they admittedly do not rely on features of current physical theories. Nothing important for my purposes hangs on the question of what to call the approaches, though, so for simplicity I will present them broadly in Poland’s terms.

17 _{Note that starting off by opposing the mental and the physical is a considerably stronger move than the} typical physicalist admission that ‘mental’ can be picked out and distinguished in virtue of attributes which are at least not prima facie physical.

18 _{The view persisted well beyond the seventeenth century. Thus Kant: ‘And yet we cannot even think of living} matter as possible. (The concept of it involves a contradiction, since the essential character of matter is lifelessness, inertia.)’ (1987: 394).

overdetermination, what is needed to get the argument going is any plausible completeness premise. They then consider two versions of the overdetermination argument, one involving a negatively characterised completeness premise concerning the completeness of the non-mental.19 I return to this point in section (6) below.

Turning for a while to a posteriori strategies, Poland (1994: 113-4) considers a well known proposal by Meehl and Sellars (1956) who distinguish between ‘physical1’ and ‘physical2’ as follows: 20

physical1: terms employed in a coherent and adequate descriptive, explanatory account of the spatio- temporal order.

physical2: terms used in the formulation of principles which suffice in principle for the explanation and prediction of inorganic processes (1956: 252).

Although it might seem as though physical1 begs the question against, inter alia, the dualistic

interactionist and emergentist, this is not actually the case. The purpose of physical1 is not to pre-empt such

metaphysical considerations, but rather to capture the idea of a comprehensive and broadly scientific system of knowledge about the world. Both sides of Descartes’ substantial dualism would comfortably find places in

physical1, as long as the purely temporal could be regarded as part of the ‘spatio-temporal order’. Poland has it

that physical1‘was intended to capture the full vocabulary of natural science’ and objects against it that the form

of physicalism it leads to is ‘much too weak’ (1994: 114). Both claims seem questionable, though. There is nothing about physical1that rules out the social sciences, economics, or psychology. Furthermore, it is far from

clear that the purpose of physical1 was ever to characterise the physical per se (why else is there a separate

account of physical2?) but rather to set a general limit on what would be admissible as science. Certainly no

interesting physicalist conclusions could be expected to follow from arguments concerning the relatively undiscriminating physical1, for the reason noted more than once already, that physicalism is most naturally seen

as a thesis about at least two classes of properties. Although Poland seems to expect physical1 to do more work

than Meehl and Sellars did, my purposes also require a more narrow or restrictive characterisation of physical. Indeed, Poland is, surely, correct to contend that ‘[t]he strength and significance of physicalist doctrine is, ceteris paribus, inversely proportional to the extent of the bases’ (1994: 114). And it is precisely because

physical2is considerably narrower that it seems more significant and perhaps also promising for my purposes.

Poland has a number of objections to it too. He points out, for example, that it lacks an ‘independent

19 _{One of these is based on the proposal that the ‘non-mental’ might be complete, and the other that the} scientifically ‘quantifiable’ might be. In both cases given the completeness premise an identity argument can be constructed.

20 _{Feigl (1958) adopts the Meehl and Sellars (1956) approach with some minor modifications, and continues to} use the concept of the ‘inorganic’ to characterise his version of physical2. He renders physical2 as ‘... the kind

of theoretical concepts (and statements) which are sufficient for the explanation, i.e. the deductive or probabilistic derivation, of the observation statements regarding the inorganic (lifeless) domain of nature’ (1958: 424).

characterisation of what ‘inorganic’ means’ and that by implication it ‘lumps together physics and chemistry’ (1994: 115). Neither objection need be particularly damning, though, since while the exact boundary between organic and inorganic may well be vague, there manifestly is a great deal of unforced and untutored agreement about which things to count as living and which to exclude. Given this, ‘inorganic’ is a pretty useful way of discriminating a domain of phenomena, and could quite plausibly be regarded as a rather general natural kind. Not only that, there does not seem to be anything especially disastrous about combining physics and chemistry, especially not for Poland’s purposes as a physicalist.21 The exact relation between physics and chemistry is surely an empirical question, and the notion that chemistry is properly seen as a part of physics commands significant support.22

Poland also objects, following Chomsky (1968: 83) and Block (1980) that an account of physics based on physical2 cannot handle the possibility of some kinds of emergent physical laws, specifically ones which

come into play only in certain organic contexts, such as brains of certain sizes or degrees of complexity. Block puts the objection as follows:

Briefly, it is conceivable that there are physical laws that ‘come into play’ in brains of a certain size and complexity, but that nonetheless these laws are translatable into physical language, and that, so translated, they are clearly physical laws (although irreducible to other physical laws). Arguably, in this situation, physicalism could be true—though not according to the account just mentioned (i.e.

physical2) of physical property (Block 1980: 296, quoted in Poland 1994: 116).23

This suggestion should not be mistaken with the more standard notion of an ‘emergent’ law where the law which emerges from a physical configuration is generally not itself regarded as physical.24 _{Rather the key} idea is of genuinely physical laws only manifest in some organic, or perhaps otherwise specialised,25 contexts, a type of emergence which Poland describes as ‘innocuous’ as far as physicalism goes (1994: 117).

There are at least two issues here, and Poland’s account suggests that he may be confounding them to some extent. On the one hand there is the issue of emergent physical laws, and on the other the specific notion of emergent laws associated with, say, organic systems. Obviously an emergent law which still fell properly

21

Chemistry has been the site of a recent emergentist revival, but since Poland makes no reference to this phenomenon his protest seems somewhat forced, especially since nothing in his wider argument indicates that he is especially committed to physicalism about chemistry. The question of emergence in chemistry is discussed below in Chapter Two, especially sections (2.1) and (7.1).

22 _{See Oppenheim and Putnam (1958: 22, 27), Smart (1989: 82), McLaughlin (1992) and Chapter Two below.} 23 _{Block’s argument is offered in an endnote where he is considering the view that a physical property is a}

‘property expressed by a predicate in some true theory adequate for the explanation and prediction of the phenomena of nonliving matter’. Compare McLaughlin on the scope of physics (1992: 53).

24 _{Emergence is discussed in more detail in Chapter Two below, and Block’s proposal is considered specifically} in section (3.2) of that chapter.

25

The question of the status of physical relationships, including laws, which may be limited to specific specialised conditions is discussed in more detail in Chapter Four below.

within the domain of the inorganic would present no difficulty for physical2. Such a law could reasonably be

expected to manifest itself in suitable inorganic contexts, and could also reasonably be expected to be the kind of thing physicists could find out about. Furthermore, it is at least unclear why we would want to maintain that a law obtaining only in organic systems, or some sub-set of them such as mammalian brains or the frontal lobes of transformational grammarians, would be properly thought of as physical. Block’s stipulation that the law in question be translatable into the language of physics is insufficiently specific. Two ways in which it could be on the wrong track are, firstly, if he means either that the law be somehow added to physics so that the ‘translation’ would be a trivial achievement, or, secondly, if he is begging the question against the view that such a law would not be physical at all. Indeed our putative nomological oddity would seem to be a prime candidate for being recognised as a psychological or biological law, and that is exactly how most of the traditional emergentists would have seen it too.26 For the time being I will treat Block’s objection as not being damaging to physical2 as an account of physical, and return to the problem in the course of the discussion of

emergence in Chapter Two below.27

Poland (1994: 117) is surely correct, then, to shift some of the burden here onto the Block-style objectors, and demand that they offer some characterisation of ‘physical’ which makes sense of the objection, and also that they give some reason to take the speculation seriously. Poland also, though, decides that

physical2 has been found unacceptable, largely as a consequence of Block’s worry, and continues with his

survey, turning to the proposal that the meaning of ‘physics’ can be left to the physicists, or in some way read off the practices and conclusions of physicists (Poland 1994: 118). Nevertheless, he correctly points out that this fails to solve the problem for a range of reasons. Of the reasons he cites, the two most important for my purposes are, firstly, that such a proposal is of no direct use, since we still need to know how significantly to tell who the ‘physicists’ are, and secondly that unless we mean current physics we have not made any advance either. As noted above, if we do mean current physics, then the claim that physics is complete is almost obviously false, a point Poland also recognises (1994: 119).28

Despite this, there are those (including Feigl 1969, Lewis 1983, Putnam 1983) who hold that ‘the physical is defined by modest extensions of current physics that are similar to it’ (Poland 1994: 119). Poland contends that these approaches do not really deal with the problem here, for a range of reasons including their failure to specify the ways in which modestly extended physics will be permitted to vary. Poland concludes

26 _{See Chapter Two below, especially sections (2) and (3). Note that Feigl (1958: 377) accepts physical} 2 if ‘emergentism is not required for the phenomena of organic life’, and inclines to the view that physical2 will hold the field against emergence.

27 _{In section (6) below I adopt an account of physical which is very close to physical}

2.

28 _{It is worth noting, though, that if we take ‘physical’ as something like a natural kind, then ‘physicists’ are the} people who try to figure out what the extension of the kind is. See the discussion of Snowdon in section (5.2) below.

that approaches tied to current physics even in this qualified way are unacceptable, and continues to seek a more general, and in his terms a priori, account of ‘physical’. I would argue, though, that Poland’s rather swift and impatient rejection of the views in question obscures some important points that are being made. Putnam puts it as follows:

I shall assume that the fundamental magnitudes are basically the usual ones: if no restraint at all is placed on what counts as a possible ‘fundamental magnitude’ in future physics, then reference or soul

or Good could even be ‘fundamental magnitudes’ in future physics! I shall not allow that naturalist the escape hatch of letting ‘future physics’ mean we-know-not-what. Physicalism is only intelligible if ‘future physics’ is supposed to resemble what we call ‘physics’ (Putnam 1983: 212).

Putnam is surely correct to maintain that the handing out of blank cheques to physicists by proposing unconditionally to be physicalist about whatever they eventually decide is philosophically poor form. His point has much in common with Chomsky’s (1968) warning, briefly discussed in section (3.2) above, that without some kind of qualification or restriction the category of ‘physical explanation’ is unlikely to be able to do any discriminating work. That point has already been noted and discussed, though. What I want to emphasise now is that some kind of attention to present, and even previous, physics is unavoidable when we attempt to consider what it would be reasonable to expect from future or ideal physics. Whatever we can reasonably expect from a future or ideal physics has to have something to do with the state of present physics. In Chapter Four (section 6) below I return to the question of how best to make use of the limited evidence available from physics in its current state.

Not only that, Poland simply seems to have misunderstood Lewis. In the text to which Poland refers, Lewis characterises what he calls Materialism as ‘the thesis that physics – something not too different from present-day physics, though presumably somewhat improved – is a comprehensive theory of the world, complete as well as correct’ (1983: 361). As always it is important to keep one’s modal ducks in a row when reading Lewis, whose point here is to assert something about the actual world, rather than to offer a general definition of physics which would pick out some specific set of properties at any world. Lewis’s view is that at any world there will be some minimal set of properties, which he calls the natural properties, underlying the various processes and changes which take place at that world. He also maintains fallibly and empirically that at the actual world the set of natural properties is pretty close to the basic properties of current physics.

Poland concludes his survey of a posteriori approaches by claiming that the need for a broadly a priori

distinguishing criteria for distinguishing ‘physical’ seems more urgent than ever, and stating that ‘[s]trategically, the problem for the physicalist is that, unless there is some antecedently specifiable principle for identifying the physical bases, physicalism cannot be formulated in significant ways’ (Poland 1994: 119).

Poland’s first candidates for a priori strategies are similar proposals by Lewis and Quine, to the effect that physics can be regarded as ‘the branch of science whose goal it is to provide a comprehensive supervenience base’ (1994: 120). Thus:

One motivation of physics down through the centuries might be said to have been [...]: to say what counts as a physical difference, a physical trait, a physical state. The question can be put more explicitly thus: what minimum catalogue of states would be sufficient to justify us in saying that there is no change without a change in positions or states? (Quine 1979: 163-4).

Physics (ignoring latter-day failures of nerve) is the science that aspires to comprehensiveness, and particular physical theories may be put forward as fulfilling that aspiration. If so, we must again ask what it means to claim comprehensiveness. And again, the answer may be given by a supervenience formulation: no difference without physical difference as conceived by such and such grand theory (Lewis 1983: 356-7).

Prima facie this seems as though it can’t be quite right. Poland (1994: 120) has it, getting at part of what wrong here, that ‘Quine and Lewis appear to have confused the aims of physics with the aims of physicalism’, in other words that it seems mistaken to impute to physicists any particular interest in philosophical positions such as supervenience. Physicists might plausibly want to be eliminativists, for example. If we consider the worlds at which some physics is in fact complete, then a consequence of the completion of the work of physics would be that a supervenience base for other phenomena had been developed only at some of those worlds. But the supervenience base at some world (if there is one) need not be purely physical, so being part of a supervenience base cannot be a criterion for being physical. Not only that, the Completeness Thesis on its own does not entail what metaphysical dispensation will obtain at any given world at which it is true, since completeness is compatible with, inter alia, zombie worlds, qualia rich worlds, preëstablished harmony. If physicalists are to be correct then science must in principle be able to do what Quine