A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 GrzeGorz BuGAjAk depArtment of methodoLoGy of system And informAtion sCienCes institute of phiLosophy, CArdinAL stefAn Wyszyński university, WArsAW Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories Abstract The irst part of the paper is a metatheoretical consideration of such philosophy of nature, which allows for using scientiic results in philosophical analyses. An epistemological ‘judgment’ of those results becomes a preliminary task of this discipline, and this involves taking a position in the controversy between realistic and antirealistic accounts of science. It is shown that a philosopher of nature has to be a realist, if his task to build true ontology of reality is to be achieved. At the same time he cannot be a realist – a possibility that science itself is capable of deciding what beings really exist (a typical realistic claim is that scientiic notions refer to something external and truly describe its characteristics) has to be denied, if the philosophy of nature is seen as a discipline investigating the natural world, while being epistemologically different from the natural sciences. A possibility of weakening this opposition is explored in the second part of the paper, where the idea of so-called “postulated ontology” of scientiic theories is brought to the consideration. This idea appears in the context of a well-known thesis of the underdetermination of scientiic theories by empirical data. It is argued in the paper, that the conviction of the existence of some kind of relation between a given theory and ontological ideas can be derived from this thesis, regardless of its particular form. Therefore, certain solutions to classical philosophical questions can be obtained, in principle, by careful inspection of scientiic achievements. However, if the thesis of underdetermination holds, such philosophical A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 60 Grzegorz Bugajak solutions are not imposed by science itself. In order to arrive at some kind of ontology based on science, it seems necessary to accept certain philosophical presuppositions in the irst place. This and the fact that scientiic theories change in time show that although such a kind of ontology is possible, and perhaps desirable, it can never be ultimate. Key words: philosophy of nature, realism, ontology of scientiic theories. 1. Philosophy of nature and natural sciences. Introductory remarks Philosophy of nature is nowadays understood and practiced at least in a few ways. In spite of quite signiicant differences between various trends within this discipline, its representatives would probably agree that philosophy of nature is the theory of the material world, that is – reality accessible in the sensory cognition1, and that its purpose is to construct the ontology of this world, i.e. to determine the nature (the essence), structure and properties of material beings [cf. Such, Szcześniak 2001, 21]. Similar deinitions can be found both in the older and more recent works concerning the metatheory of this discipline: “(...) philosophy of nature should be a rational theory of the whole material reality. (...) Thus, the main task of philosophy of nature is to examine the organization of nature, the fundamental level of reality, and the fundamental structure of the material world” [Lemańska 1998, 32-33]; “(...) philosophy of nature is a philosophical discipline (...) the subject matter of which is the material world as a whole (...) and the essence of the most universal properties of the bodies available for human senses” [Mazierski 1972, 46]. From such a deinition of the subject matter and purpose of the philosophy of nature, there 1 Such a deinition of the subject matter of philosophy of nature may seem a bit controversial because of its gnoseological character. However, it brings the advantage of avoiding the dificulties connected with an indirect attempt of pointing to the subject matter of this discipline through the prior deinition of the notion of ‘matter’. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 61 follows the necessity of ‘defending’ the relevance of its existence in the face of rapid development of natural sciences, which examine the same subject matter and set for themselves similar purposes2. Such development, as many thinkers claim, leads towards the gradual takeover of the issues of philosophy of nature by particular disciplines of natural sciences, and as a result, towards its disappearance. This is obvious that many problems, formerly dealt with within the philosophy of nature, are now successfully solved by natural sciences. One of the examples here is the issue of motion, dealt with as early as by Aristotle, and solved in a wrong way, as we know now. Its correct solution is the product of modern physics [cf. Heller 1993, 25-27]3. This example indicates also something more than merely the fact of taking over philosophical issues by natural sciences. On the basis of such examples, one can assert that natural sciences can better cope with the issues taken over from philosophy, hence leaving them there within the scope of philosophy is harmful for our understanding of the world. Yet, it is rather obvious that the historical fact that some issues, indeed, gradually were moved into the scope of natural sciences and are solved there in a more accurate and correct 2 The classical line of ‘defence’ of philosophy of nature as an autonomous philosophical discipline (performing different tasks than, e.g. offering a synthetic picture of the world, which none of natural sciences does, because of high degree of their specialization), involves showing that although its subject matter is identical with the one of natural sciences, its purpose is different. It is – as I already pointed out – to comprehend the essence of material beings, and the very notion of the ‘essence’ as the one of ‘being’, is a purely philosophical one. Hence, natural sciences deal with the phenomenal side of reality, while philosophy of nature deals with the sphere of the essence of being. Moreover, philosophy would answer the ‘why’ questions, while natural sciences the ‘how’ ones. However, many philosophers treat these distinctions as purely verbal ones, and they do not deny natural sciences’ capability of having an insight into the ‘essence’ of things, or their competence of answering the ‘why’ questions. We do not take any stand in the argument just outlined; here we just make an ‘optimistic’ assumption that philosophy of nature has something to deal with. An attempt of justifying this assumption will be presented below. 3 This is about motion, which in Aristotelian philosophy is called local motion. It’s worth to remember that this philosophy developed also a broader notion of motion understood as any possible change. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 62 Grzegorz Bugajak way, does not mean that it is the case with all philosophical problems. This historical process can be seen as a natural consequence of the increase of knowledge and the specialization of its disciplines, and of growing awareness of their epistemological distinctness. If, as it is often claimed, the beginnings of the rational relection upon the world have their sources in ancient Greece, and these sources are philosophical in nature, the thesis of transferring certain issues from the scope of philosophy to the one of natural sciences has to concern a lot of them. However, it is no reason to suppose that this process signiies some epistemological regularity and that philosophy of nature has to end up as a member of the group of honorable but dead ‘monuments’ of culture. The ‘defense’ of philosophy of nature – at least at its initial stage – may involve pointing to the problems, which although concerning the material world, are not dealt with within natural sciences4. One of them is, for instance, the issue of causality principle – the question whether this principle is in force in the whole of nature, or maybe there are some absolute exceptions, namely, events, which are absolutely accidental. Although natural sciences shed some important light on this problem, they are unable to solve it on their own, since the notions of ‘cause’ and ‘chance’ are employed in them in a narrow and speciic sense. Similarly, an attempt of answering the question of the essence of life, although it can’t do without important information provided by biological sciences, it is still beyond their abilities, as numerous and non-equivalent deinitions of life indicate. Like the examples of the issues successfully taken over from philosophy by natural sciences are not the ‘evidence’ for the redundancy of the philosophy of nature, the examples of the issues remaining within its scope – regardless of the fact that the competence of philosophy of nature to deal with them may be a matter of debate – do not constitute its proper epistemological foundation. Nevertheless, this article is not devoted to the formal justiication of philosophy of nature, so the above remarks may be treated as an attempt to give preliminary reasons for our ‘optimistic assumption’ that philosophy of nature exists nowadays because there exist problems which it can deal with. 4 Such strategy is used, e.g. by Lemańska [1998, 32-36]. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 63 One more problem concerning the relation of philosophy of nature to natural sciences is the question whether it can or cannot (should or should not) utilize the results of these sciences. The opponents of making the philosophy of nature dependent on natural sciences indicate that the variability of the latter and frequent modiications and even repudiations of their conceptions threaten philosophy with similar ramiications: the solutions arrived at cannot be ultimate – the change in the ‘scientiic background’ of philosophy practiced in this way has to result in the revision of philosophical conceptions; constant revision, because scientiic conceptions are subject to such a constant and unpredictable variability. We have to admit that philosophy of nature which utilizes the results of natural sciences, actually pays such a price and doesn’t realize the ideal of philosophia perennis. This cost, however, is worth bearing because philosophy gets in return the more thorough insight into reality, theory of which it seeks to construct. Moreover, the starting point of philosophy was, from its very beginning, casual knowledge. Although scientiic knowledge is different from its casual form, this difference doesn’t concern its very essence, but only its degree: scientiic knowledge is more critical and, certainly, more precise [Lubański 1966, 250]. Thus, if philosophy can depart from casual knowledge, it also can take into account the results of the more perfect scientiic knowledge. Those few remarks do not demonstrate the complexity of the issue of the possibility of utilizing the natural sciences results by philosophy of nature, so they can be treated, as the previous ones, as a kind of assumptions. Then, there are two assumptions which were argued for only very briely. These are: (1) the ‘optimistic’ assumption concerning the existence of philosophy of nature, and (2) the necessity of utilizing the results of natural sciences by philosophy. An attempt to practice the philosophy of nature, the possibility of which is embodied in the assumption (1), with the use of the natural sciences results – the assumption (2), leads, in turn, to the important question: what position should the contemporary philosophy of nature take in the controversy concerning the cognitive status of scientiic theories? A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 64 Grzegorz Bugajak 2. Philosophical content in scientiic theories If, according to the approach proposed here, we assume that philosophy of nature can, or even should utilize the results of natural sciences, it faces the task of the ‘assessment’ of these results, the evaluation of their cognitive value. One of the objections, the opponents of connecting philosophy of nature with natural sciences raise, is that together with the results of these sciences, philosophy inherits some elements of the picture of reality, being rooted, often implicitly, as deeply as in the scientiic assumptions. In other words, philosophy may imperceptibly inherit the picture of the world, which is, to some extent, mature but also somewhat distorted. That’s why, undertaking the task of the epistemological evaluation of the natural sciences results, in which the philosophy of nature expresses its caution with regard to the scientiic data it takes into account, weakens the arguments, the opponents of such philosophy raise. The task mentioned above can have a particular character – while analyzing a given philosophical problem we should ask to what extent scientiic knowledge about it can be regarded as reliable. Do we utilize here the stable and well-justiied scientiic theories or merely not necessarily coherent set of working hypotheses? For example, while considering the problem of the validity of the causality principle, mentioned above, we should analyze, from the methodological and epistemological perspective, the results of quantum mechanics concerning the occurrence of phenomena, which are subject to the statistical regularities5. The task of the epistemological ‘evaluation’ of natural sciences has also its global dimension. This is the necessity of taking some position in the metatheory of natural sciences. Because we are concerned here with similar, meta-level characteristics of the philosophy of nature, and not with its speciic issues, we should consider this very problem more thoroughly. One of the most outstanding representatives of Polish philosophy of nature in the 20th century, Kazimierz Kłósak, developed an attitude, I refer here to the almost hundred-years-old argument concerning the interpretation of quantum mechanics. 5 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 65 he himself called the empiriological theory of natural sciences; he justiied it as opposed to the so-called ontologizing theory. According to the latter, scientiic knowledge either naturally turns itself into metaphysical or philosophical knowledge, or (which can be regarded as a more moderate statement) philosophical conclusions directly follow from natural sciences [Kłósak 1980, 22]. The empiriological theory, however, denies these possibilities, by maintaining that there is no such transformation or inference at all. Thereby, it leads to the thesis of the distinct cognitive ields, asserting that the natural sciences and philosophy of nature are autonomous with respect to each other, which can be seen, for example, in their distinct methods and purposes of research. Building up a philosophical theory of the natural world (material reality) is a different cognitive activity than examining the same world within natural sciences. The empiriological theory of natural sciences is closely related to one of the more general achievements of the 20th century philosophy, namely the clear, as it seemed, distinction of the philosophical and scientiic issues. Regardless of the failure of the neo-positivists’ program, a part of which was an attempt to point to the issues natural sciences can rationally deal with, and to separate them clearly from the problems lacking empirical contents which should remain outside the scope of scientiic research – the very indication of the disjoint scope of the competence of philosophy and science remains methodologically right. The analysis of the character of science allowed for showing that what lies within the scope of its interest is, as it is often called, the phenomenal aspect of the material world. In turn, all the questions concerning the nature of this world, the objects situated at the ‘deepest’ level of reality, and thus constituting the world, in other words, the issues traditionally called ‘ontological’ remain exclusively within the scope of philosophy6. It doesn’t matter here whether such questions are simply excluded from science or they are generally regarded as being wrongly formulated, and the ontological issues – as lacking the cognitive substance altogether. What is meant here is the separation, which would appear correct, of ontological issues from scientiic ones. Cf. also footnote 2. 6 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 66 Grzegorz Bugajak The empiriological theory is justiied, particularly, in the research practice of natural sciences [Kłósak 1980, 29], the theories of which are empirically veriied – in the observation and experience. This empirical foundation of natural sciences makes the standard scientiic practice having to ultimately reject such conceptions which cannot be veriied in this way7. Scientiic theories, in the proper meaning of the notion, are only those which are empirically adequate. There are many different attempts to elaborate the notion of the empirical adequacy, relevant to our considerations. The simplest deinition says that a theory is empirically adequate if all of its observational consequences are conirmed by experience. Historical examples of scientiic theories, however, indicate that this deinition is too strong, in the demand that all consequences are conirmed. One of such examples can be Dirac’s electron equation. One of its solutions described the electron properly, while the other was initially repudiated as being ‘non-physical’, because at that time there was no known object which could be described by this solution. Only the subsequent discovery of positron showed that this solution is also empirically meaningful. Nevertheless, at the very moment of its emergence, Dirac’s theory was not empirically adequate, in the above sense, although it was correct. That is why, the criterion of empirical adequacy, which should serve to distinguish between correct and incorrect theories, The imprecise notion of ‘foundation’ used here deliberately signals that we are not concerned with taking any position with regard to the methodological character of scientiic theories (the inductive, hypothetical-deductive or some other model), or in the debate between veriicationism and falsiicationism (in particular, the notion of empirical veriication used here is not opting for the irst of the two conceptions just mentioned). We only want to draw attention to the elementary fact of the connection between scientiic theories and empirical data. We also leave without further comments those proposals which call for reformulating the methodological characteristics of science in such a way that this connection with empirical data could be regarded as unnecessary for scientiic theories. These proposals usually are put forward to defend those scientiic conceptions which are, at least nowadays, incapable of being empirically conirmed. Recognizing these conceptions as valid scientiic theories does not conform, as we said earlier, to the standard and long established research practice of natural sciences. 7 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 67 should be weakened. One of the attempts of such a weakening is the requirement that if a theory is to be recognized as empirically adequate, hence correct (good), the vast majority of its observational consequences should be conirmed by the experience. Yet, the replacement of the phrase ‘all’ with ‘vast majority’ makes little difference for the deinition of the empirical adequacy. As it is impossible to deine this ‘vast majority’ of consequences when not knowing all of them. And this, in turn, is impossible either not only for practical reasons (we could ask how we are sure that we know all the consequences of the theory), but also in principle. Since the set of observational consequences of the theory, understood as the set of all observational sentences, which logically follow from the set of sentences constituting the theory, is potentially ininite8. This dificulty can be overcome through further weakening the notion of empirical adequacy – an empirically adequate theory is such that the vast majority of its observational consequences, known from the literature, is conirmed by experience [Zeidler 1993, 46-48]. This approach actually solves the problem because the set of the consequences of the theory, which are subject to empirical veriication, is then inite, thus the notion of the ‘majority’ of consequences becomes clearly deined. It seems, though, that the adequacy understood in this way is a highly impractical criterion, particularly in the face of largely growing number of works, constituting the so-called ‘literature’ in each scientiic discipline. I can suggest one more deinition of the empirical adequacy, which, as it seems, lacks the disadvantages just discussed: an empirically adequate theory is such that it has at least one observational consequence empirically conirmed, and no empirical evidence known so far negates any consequences of this theory. The justiication of the empiriological theory of natural sciences, indicating that the very essence of these sciences is their connection with empirical data, leads, as we have already seen, to the notion of the empirical adequacy of scientiic theories. This notion is, however, Here, we conine ourselves only to the classical – sentential – approach towards scientiic theories. 8 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 68 Grzegorz Bugajak characteristic of anti-realistic analyses of science. Thus, it turns out that supporting the empiriological theory of natural sciences implies the anti-realistic position in the debate on the cognitive status of scientiic theories9. This conclusion gets even more justiied if we look at the realist’s position with regard to the nature of scientiic theories. The realistic viewpoint, as opposed to the anti-realistic one, can be expressed with the following proposition: “If a scientiic theory is really true, there exist in the world exactly those beings, which it says about, and they have exactly those properties, which the terms of the theory attribute to them” [Hooker 1987, 7; quot. after: Zeidler 1993, 26; back-translation from Polish]. Although one may doubt whether this proposition expresses the realistic viewpoint accurately, or we may point to some other, not equivalent deinitions of realism, the conviction about the existence of the referents of the notions used in scientiic theories, known as the ‘theory of reference’ is an important element of realism in any shape. Yet, the statements about the existence of certain beings in reality are explicitly philosophical. So, if one denies the possibility of direct formulation of philosophical conclusions in natural sciences, which is the core thesis of the empiriological theory of these sciences, one has to reject the theory of reference and, together with it, the position of realism. The relation between the empiriological theory of natural sciences and the anti-realistic position emphasizes an important problem of the philosophy of nature, which permits, according to the assumption made at the beginning, utilizing the results of natural sciences. If we treat these results in accordance with the empiriological theory, i.e. in the anti-realistic spirit, we have to admit that scientiic theories, which the philosophy of nature wants to use in its considerations, are not true in classical sense, but they are only empirically adequate. Thereby, the results, which the philosophy of nature can arrive at have to have analogical character. Thus, if this discipline is aimed at constructing an So, we should give the positive answer to Lemańska’s question [Lemańska 1998, 96]: “Don’t we understand natural sciences in an anti-realistic way, if we adopt the empiriological theory of them?”. 9 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 69 ontology of the material world, such ontology cannot be true but only empirically adequate. Yet, the notion of the ‘empirically adequate ontology’ seems to be self-contradictory. The philosophy of nature, after all, aspires to build up the true picture of the world. Thus, the philosophy of nature, within such approach, becomes impossible. A rescue for the philosophy of nature may be the constatation that scientiic theories are nevertheless true, or, strictly speaking, they can be so; the notion of truthfulness can be applied to them. It, therefore, means the negation of the anti-realistic position and hence the empiriological theory of natural sciences. As we may remember, the alternative is the ontologizing theory. But if we adopt it, we will have to negate the theory of the separation of cognitive ields (philosophical and scientiic ones) and also admit that we can arrive at philosophical conclusions within scientiic knowledge. Then, the philosophy of nature, as an autonomous ield of knowledge, the subject matter of which is the material world, becomes redundant. It appears that a philosopher of nature must be a realist, if he wants to hope that his considerations reach their aim, which is to construct an ontology of the material world. But, at the same time, he cannot be a realist if he wants to remain a philosopher of nature and if he wants to maintain that this discipline has the reasons for its existence, in the face of the development of natural sciences. Is there any solution for this dilemma in which the philosophy of nature should be recognized either as impossible (if we accept the empiriological theory and its consequent anti-realism) or as redundant (if we adopt the ontologizing theory and the realism it supposes with respect to the cognitive status of scientiic theories)? The solution may be, as it seems, sought in the weakening of the ontologizing theory through the constatation that although philosophical conclusions do not follow directly from scientiic theories, some suggestions of the answers to philosophical questions may be implied by the latter. This possibility is connected with the notion of the ‘postulated ontology’ of scientiic theories. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 70 Grzegorz Bugajak 3. The ‘postulated ontology’ of scientiic theories As it was said already, the clear distinction between scientiic and philosophical issues can be seen as one of the achievements of the 20th century philosophy. However, somewhat paradoxically, the more recent results of philosophical relection upon science seem to question the conviction about the lack of connection between scientiic achievements and philosophical theses concerning reality. The conviction that certain ontology is connected with scientiic theories10, accompanies some theses, formulated and analyzed within the contemporary philosophy of science, where the notion of ‘postulated ontology of scientiic theories’ appears more or less explicitly. The above phrase concerning a rather unclearly deined ‘connection’ of a scientiic theory with ontology is deliberately imprecise. It is dificult to ind in the literature precise deinitions of such phrases like ‘postulated’ or ‘supposed’ ontology of a theory, although these very phrases appear quite often in philosophical relections upon science. We will present a few examples of such deinitions and we will try to clarify their meaning. 3.1. The ‘postulated ontology’ and the thesis of underdetermination One of the contexts, within which the reference to the ‘postulated ontology’ appears, is the well-known thesis of the underdetermination of theories by empirical data. This thesis is formulated in many varying ways. Yet, regardless of its formulation, in the majority of its versions, some ontological reference can be seen. Such a reference occurs expresis verbis within Willard Van Orman Quine’s approach, called by Paweł Zeidler the ontological version of the thesis in question. It claims, in its weaker version, that there are some theories in science, 10 Most frequently, what is meant is some ontology connected with a given scientiic theory. I don’t want to suggest – and this is not the intention of this article, either – that there exists one ontology associated with several scientiic theories (not to mention all of them). A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 71 which are empirically equivalent, but “varying with respect to the postulated ontology” [Zeidler 1993]. In its stronger version it claims that for every theory its ontologically not equivalent counterpart can be found, with empirical equivalence maintained. Empirically equivalent theories are deined as those which have the identical set of empirical consequences and this set is deined as consisting of observational sentences which can be derived from those theories. Whereas the empirical equivalence can be deined precisely enough, the ontological (non)-equivalence seems to be an unclear notion. Before we attempt to give this notion more precise meaning, let’s note that this ontological reference can be discovered also in some other formulations of the thesis of underdetermination. In those approaches, not only, contrary to the one discussed above, is there no direct reference to ontology, but also they are not equivalent to it. The most wide-spread version of the thesis of underdetermination is called the Duhem-Quine’s thesis. It says that any theory can be saved in the light of any empirical evidence11 through changing the assumptions accompanying this theory. It is not concerned with the explicit assumptions of the theory itself, which can be regarded as its constituent parts, but rather with the assumptions – as Zygmunt Hajduk [2000, 159] puts it – “of the system concerning the nature”, whose part the theory under consideration is. These assumptions are sometimes identiied with Kuhn’s paradigms, in one sense of this term, where the change of paradigm is understood as a revision of certain fundamental ontological assumptions tacitly made at a given stage of science development. This identiication seems too strong because within the context just discussed, it would mean that every empirical anomaly would have to lead either to the rejection of the theory within which it emerged, or – with an attempt to save the theory – to the revolution in science. Scientiic practice shows that such an extreme approach is not valid. Nevertheless, the change of the assumptions of the “system concerning the nature”, or rather making some corrections in these assumptions [Hajduk 2000, 159], can be regarded as the change taking 11 Thereby, it questions the effectiveness, but not the validity of Popperian fallibilism. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 72 Grzegorz Bugajak place within some ontological intuitions associated with a given scientiic theory. This attitude seems to be justiied by Quine’s views, to which we will return later in our article. At this point, let’s just note that Duhem-Quine’s version of the thesis of underdetermination contains some ontological connotations. Another version of the thesis of underdetermination, called the linguistic approach [Zeidler 1993] can be found in Kazimierz Ajdukiewicz’s works. He claimed that the scientiic picture of the world is not unambiguously determined by empirical data, but it depends on both these data and the notional apparatus adopted [Ajdukiewicz 1934]. The phrase “the scientiic picture of the world” should, in the irst place, be understood as referring to the whole of knowledge about the world, embodied in scientiic theories. Its understanding is, therefore, strongly dependent on the accepted epistemology of scientiic knowledge. An interpretation of this version of the thesis of underdetermination in the spirit of moderate realism (whose validity we won’t discuss here, but which is connected – as we could see – with the ontologizing theory of natural sciences; and in this article we support some weakened version of this theory) allows for the statement that this “scientiic picture of the world” contains also some theses traditionally regarded as ontological. Thus, the approach just outlined means that empirical data do not unambiguously determine the ontic structure of the world hidden ‘under the surface of phenomena’. The various versions of the thesis of underdetermination are, as we already said, not equivalent; they differ mainly with respect to the sources of underdetermination, which they indicate. However, regardless of the differences between them, each of them seems to imply a conviction that some form of ontology is hidden within scientiic theories. This conviction most frequently takes the form of some vague intuition and such notions as ‘postulated ontology of scientiic theory’ are usually not properly deined by those who employ them. The wider context, in which they appear, allows, in some cases, for at least preliminary speciication of these notoriously imprecise notions. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 73 3.2. The notion of ‘postulated ontology’ – an attempt of speciication Some clariications with regard to the notion in question were done by Quine himself in his book Pursuit of Truth [1990], where he undertook the task of updating and summarizing his views, among other issues, on the objective reference of scientiic knowledge. He presents there the idea of ‘ontological relativity’ according to which it doesn’t matter what we recognize as the basic component of reality: material particles, waves propagating in space or anything else. What matters is only the predictive power of scientiic theories which is independent of our beliefs on what is ‘ultimate’ object of these theories. What objects or ‘things’ which we decide to recognize as existing does not matter for the truthfulness of the observational sentences, which are the beginning and the end of scientiic knowledge [Quine 1990, 56; cf. Quine 1981, 21]. This idea can also be expressed in the language of mathematical models of phenomena: among various models of a given phenomenon, there can exist a class of equivalent models, namely those which have identical set of consequences. A phenomenon ‘in itself’ doesn’t impose in any way the choice of the model, belonging to the class of the equivalent ones, which should be used for its description. The criterion of such choice is, therefore, external to the phenomenon. It can be, for example, the convenience in using a given model. This is the case, for example, in electrostatics12. While describing the force affecting a given object, we can use the model of the electric ield and interpret the symbols at the right side → → of the equation F = qE in the following way: q – a parameter de→ scribing a property of a body (called the electric charge); E – a parameter describing a property of the space in which the body is situated (called the electric ield intensity). 12 Analogical remarks apply to the classical theory of gravitation. A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Grzegorz Bugajak 74 The formula for the electrostatic force can also be shaped in accordance with the model of two interacting charges, in the following form: q1q2 1 ––– F = ––– . 4�εo r122 → → Both models are equivalent. In both of them, there occurs the notion of the electric charge as a property of a given body. Only the irst one, however, employs the notion of the ield, which turns out to be very useful in describing electrostatic phenomena. Nevertheless, it could basically be eliminated from the contemporary electrostatics, at the expense of losing this convenience, and we could use only the other model of the interacting bodies. Thus, a scientiic description of a given phenomenon may be ambiguous in the sense that we can use in it such models, which are equivalent with respect to their consequences, but distinct with respect to the notions they use. While we look for the ‘postulated ontology’ in such a theory, there arises a question about the priority of the choice of the model; the question to which notions we can attribute some philosophical content by way of predicating that a given thing exists in reality or a given process takes place. Can we, for instance, say that the electric ield exists? This question seems invalid because of the ambiguity of the scientiic description indicated. Science does not favor any of potential equivalent models, and thereby it doesn’t entitle to attribute the actual existence to the referents of the notions employed in these models. Therefore, this is mere convenience which makes us customarily reify the results of scientiic knowledge. However, if, for some reason, the language avoiding clear reiication turns out more advantageous, our beliefs concerning the ‘true’ nature of the world can change radically. Although, the clear deinition of the ontology associated with a theory is dificult to ind in Quine’s works, it seems to follow from his views, expressed in Pursuit of Truth, and from the examples quoted there that he regards as ontological the fundamental, but also very general, views concerning the nature of the world, like, e.g. the question: what are basic ontic categories? However, we should note A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 75 that although, according to the ontological version of the thesis of underdetermination, an argument concerning these categories, e.g. an argument between reism and eventism, cannot be solved within science, nevertheless, the latter does provide some picture of the fundamental properties of the world. Strictly speaking, it can provide inconsistent pictures and this inconsistency is unsolvable with scientiic methods. Yet, some philosophical theses concerning basic ontic categories are possible to be ‘inferred’ from scientiic theories. Paweł Zeidler, in his work Spór o status poznawczy teorii (The Controversy about the Cognitive Status of Theories, 1993), made an attempt to deine in greater detail the ‘postulated ontology’ of a scientiic theory13. It is generally agreed that an important part of every (or at least more advanced) theory of natural sciences is the mathematical apparatus, which the theory employs, and which Zeidler calls the “mathematical scope” of the theory. Zeidler shows, with the example of classical mechanics of material points, that such a theory can have various mathematical scopes. He also outlines the way in which an equivalent of a given theory with a non-standard mathematical scope can be built up. Mathematical instruments, in turn, which are utilized in a physical theory, are based on a more fundamental mathematical theory – the set theory. These instruments can particularly be constructed on the basis of the alternative set theory. At this very point, the author arrives at some ‘ontological’ conclusions. In his opinion, the set theory is a kind of a description of the structure of space-time. In the case of classical set theory, the space-time, it describes, has a continuous structure and in the alternative version – a non-continuous one. Thus, the same physical theory (here the classical mechanics of material points14), or rather its various versions, but with the identical empirical consequences, may ultimately be based on different versions of the set theory and hence can imply a diverse picture of the space-time. Thus, An attempt to specify this deinition is not the immediate purpose of Zeidler’s work. However, the analyses he carries out allow us to infer the way he understands the postulated ontology of a scientiic theory. 14 The author does not conine himself only to this example; he shows that also the relativistic version of mechanics can be seen in this way. 13 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 76 Grzegorz Bugajak it would be an example of theories which are empirically equivalent but different with respect to the postulated ontology. Considering the attempt to elaborate the notion of the ‘postulated ontology’ outlined above, we have to note irst that the alternative set theory and the non-standard analysis based on it, although being constantly developed, most often is not treated as the equally mature and useful mathematical instrument, as the standard analysis, and it is treated rather as a kind of mathematical ‘experiment’. Yet, this is not the most important thing in the attempt just discussed. Even if we accepted the non-standard analysis as a valuable and well-developed mathematical instrument and the physical theory, built up with the use of its methods, as a fully equivalent to its classical version, there would remain the question: do such theories really ‘postulate’ distinct ontologies? Such alternative theories are based on, as it was indicated, some version of the set theory, and in each of these versions the notion of spacetime is constructed in a different way. A suggestion that it indicates alternative ontologies15 would require the recognition that, with acceptable understanding of the notion of ‘ontology’, the mathematical properties of a certain space-time structure, like being continuous or non-continuous, are identical with the properties of the world. This idea is convergent with the views of those authors who believe in the ‘mathematicality of nature’ and who claim that the proper explanation of undeniable cognitive success of the mathematized natural sciences is the constatation that the most fundamental level of reality is constituted by mathematical structures. Without going into a discussion of this attitude, let us only note here that it is a strong philosophical thesis, whose acceptance seems to narrow down the range of the potential ways of understanding the ‘postulated ontology’ of scientiic theories. Another doubt concerning relating the notion of ‘postulated ontology’ to the properties of the mathematical models utilized within scientiic theories, follows from the fact that within the same mathematical apparatus, completely different phenomena can be modeled. In The author quoted here doesn’t formulate such conclusion in a straightforward way. However, the analyses, he carried out, and the examples he gave, seem to suggest such an understanding of ontology. 15 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 77 some crucial sense, mathematical models do not have any ‘content’– they, by their very nature, lack the direct relation to reality. The possibility of using the same model for the description of physically different phenomena is certainly their strength. Nevertheless, we have to note that only when they are used in the concrete cases, they gain their physical content. An example can be the model of the so-called harmonic oscillator. In its simplest form it is the equation: d2ψ ––– + ω2ψ = 0, dt2 where t is a parameter and ψ – a function of this parameter. If some physical process can be described with such equation, the relation between certain quantity ψ and the parameter t is expressed with a periodic function e.g. in the form of ψ(t) = Acos(ωt + φ); (A, ω, φ – constants). The model of the harmonic oscillator can be used to describe such physically distinct phenomena as, for example, the motion of mechanical systems or the lux of charge in electric systems. The ‘pure’, not interpreted model, lacks any physical content. This is obvious that such a model is highly useful, because it provides schemes of solutions of many different problems. But it cannot be regarded as a characteristic description of some concrete phenomenon. Thereby, it is purely pragmatic in character, and cannot constitute a basis for any ontological proposition concerning what exist in reality. What is more, many mathematical scientiic models, particularly in physics and also in chemistry and ecology, have the form of differential equations. Functions, which are the solutions of such equations may, in turn, model the quantitative relation of a given property to the parameter(s). It can be, e.g. the change of the property w in time: w = w(t). Yet, the class of differential equations having analytical solutions, (in the form of a function) is limited. If an analytical solution of a given problem cannot be found, it is possible to calculate approximately the value w for the established values of parameters. Thus, the model provides concrete numerical predictions for the property being examined. Though it doesn’t comprehend the universal relation between this property and the parameters. We can say that, in such a case, A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Grzegorz Bugajak 78 there is no strict model of a given property. Thereby, there is no basis either for formulating ontological judgments concerning reality modeled in this way. It seems, therefore, that identifying the notion of the ‘postulated ontology’ with the properties of mathematical models employed in scientiic theories is a wrong track, as far as the attempts to clarify this notion are concerned. But it doesn’t mean that such attempts are totally pointless. The relevant search for the ontological content postulated in scientiic theories can become a research task for the contemporary philosophy of nature. 4. Conclusion The outlined viewpoints of Quine and some other authors who are concerned with the notion of the ‘postulated ontology’ of scientiic theories, indicate – regardless of their drawbacks or the controversies they raise – that these theories may indeed constitute the basis for formulating some conclusions concerning the most fundamental properties of the real world. It seems generally possible that the classical ontological issues can ind their interesting solutions in the light of the contemporary natural theories. Exploring this possibility could provide an answer not only to the most universal ontological questions, namely, about basic ontological categories, about the type of objects constituting the world, and so on, but also it could help in solving more speciic ontological problems, traditionally dealt with within the philosophical relection, e.g. the question of the nature of space and time and the question of causality. This rather unoriginal conclusion seems to follow, however, from the achievements of non-classical philosophy – from the thesis of the underdetermination of a theory by empirical data. The ontological aspects of this thesis, an analysis of which has been undertaken in this article, seems worth examining in greater detail. If the thesis of underdetermination is right, beside the suggestion – regardless of its non-equivalent comprehensions – of the existence A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 Philosophy of Nature, Realism, and the Postulated Ontology of Scientiic Theories 79 of ontology hidden in some way in scientiic theories, it also leads to one more conclusion, which deserves our attention and which is actually a warning. Such ontology is not, and never will be, given directly in scientiic theories. According to the thesis just discussed, they are ontologically ambiguous – underdetermined. Those, who treat philosophical interpretations of scientiic theories as an integral part of science in itself, (sometimes, unfortunately, very inluential scholars do so) seem to forget about the (ontological) underdetermination of scientiic theories. This situation became apparent, for instance, in the controversy over the interpretation of quantum mechanics. Certain conceptions connected with this branch of physics were recognized as valid not because they were the necessary conclusions following from the theory itself, but because they were formulated by scholars, who were rightly recognized scientists16. Finally, we should think that constructing the ontology with the use of the results of natural sciences has to be based on some philosophical pre-assumptions, which will eliminate this ambiguity. What is important, such ontology wouldn’t be completely arbitrary – its relation to the theories of natural sciences must impose signiicant restrictions on it17. At the same time, however, the variability of scientiic theories and the philosophical pre-assumptions being arbitrary make it be not ultimate either. References: Ajdukiewicz K., 1934, Das Weltbild Und die Begriffsapparatur, Erkenntnis 4, 259-287. The physicist and Noble Prize winner, Murray Gell-Mann, wrote, while analysing the reasons for domination of certain interpretation of quantum mechanics: “Bohr brainwashed the whole generation of physicists, forcing them to believe that the problem has been already solved” [Gell-Mann 1976, 29]. Cf. also an example of the complementarity principle provided by John Gribbin [1995, 115], and Michał Heller’s [1996, 16] opinion on the inluence of famous scientists on the shape of the picture of the world. 17 Here, Quine’s views seem too extreme, when he claims that we can revise and alter ontology totally freely. According to him it is possible, since if, together with altering the ontology, we also change the interpretation of all the names and predicates within the theory, the truthfulness of the observational sentences will be preserved [Quine 1994, 360]. 16 A. Świeżyński (red.), Philosophy of Nature Today, Warszawa 2009 ISBN 978-83-7072-625-6, © by Wydawnictwo Uniwersytetu Kardynała Stefana Wyszyńskiego w Warszawie 2009 80 Grzegorz Bugajak Gell-Mann M., 1976, The Nature of the Physical Universe, John Wiley and Sons, New York 1976. Gribbin J. R., 1995, Schrödingers kittens and the search for reality. Solving the quantum mysteries, Little, Brown & Co., Boston. Hajduk Z., 2000, Metanaukowy walor tezy o niedookreśloności teorii przez dane doświadczenia: stanowisko L. Laudana, in: Filozoiczne i naukowo-przyrodnicze elementy obrazu świata, vol. 2, ed. A. Latawiec, K. Kloskowski, G. Bugajak, Wydawnictwo UKSW, Warszawa, 149-170. Heller M., 1993, Fizyka ruchu i czasoprzestrzeni, PWN, Warszawa. Heller M., 1996, Naukowy obraz świata a zadanie teologa, in: Obrazy świata w teologii i w naukach przyrodniczych, ed. M. Heller, S. Budzik, S. Wszołek, Biblos, Tarnów, 13-27. Hooker C. 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