The Routledge Handbook of Scientific Realism

Juha Saatsi

• Publisher: Routledge
• Year: 2017
• Print ISBN:
  9781138888852
• eBook ISBN:
  9781351362900
• Topic: Philosophy
• Subtopic: Epistemology in Philosophy

Scientific realism is a central, long-standing, and hotly debated topic in philosophy of science. Debates about scientific realism concern the very nature and extent of scientific knowledge and progress. Scientific realists defend a positive epistemic attitude towards our best theories and models regarding how they represent the world that is unobservable to our naked senses. Various realist theses are under sceptical fire from scientific antirealists, e.g. empiricists and instrumentalists. The different dimensions of the ensuing debate centrally connect to numerous other topics in philosophy of science and beyond.

The Routledge Handbook of Scientific Realism is an outstanding reference source – the first collection of its kind – to the key issues, positions, and arguments in this important topic. Its thirty-four chapters, written by a team of international experts, are divided into five parts:

• Historical development of the realist stance
• Classic debate: core issues and positions
• Perspectives on contemporary debates
• The realism debate in disciplinary context
• Broader reflections

In these sections, the core issues and debates presented, analysed, and set into broader historical and disciplinary contexts. The central issues covered include motivations and arguments for realism; challenges to realism from underdetermination and history of science; different variants of realism; the connection of realism to relativism and perspectivism; and the relationship between realism, metaphysics, and epistemology.

The Routledge Handbook of Scientific Realism is essential reading for students and researchers in philosophy of science. It will also be very useful for anyone interested in the nature and extent of scientific knowledge.

Part I
Historical development of the realist stance

1
Realism and Logical Empiricism

Matthias Neuber

1 Introduction

This essay argues that, in order to understand realism and its roots, we need to understand the emerging realist tendencies in logical empiricism and avoid naïve juxtaposition between it and realism. However, the relation between both currents is rather intricate. On the one hand, the logical empiricists rejected realism as an outdated, unwarranted, and entirely meaningless doctrine. On the other hand, they attempted to account for a realistic understanding of the language of science. It is for this reason that, according to the logical empiricist agenda, a distinction must be drawn between ‘bad’ metaphysical realism and ‘good’ empirical (or ‘scientific’) realism. Given this distinction, the relation between realism and logical empiricism can be discussed along two lines. There is, firstly, the well-known – and rather infamous – logical empiricist critique of metaphysics, according to which the realism issue is nothing but a ‘pseudo-problem.’ However, secondly, in the philosophy of science, the logical empiricists obviously sought for a reconciliation of empiricist and realist components in our philosophical interpretation of scientific concept formation and theory construction. As will be shown in the following, there existed (at least) three varieties of such a conciliatory view: a ‘probabilistic,’ a ‘pragmatic,’ and an ‘invariantist’ version of the intended ‘empirical realism’. Yet in order to adequately understand the logical empiricist approach towards the debate over realism, we first need to consider the ‘canonical’ anti-metaphysical attitude.

2 Against ‘metaphysical’ realism

What is metaphysics? According to the early logical empiricists – especially the members of the Vienna Circle – a sentence proves metaphysical if it cannot be verified by means of perception or (in more liberal terms) observation. No wonder, then, that realism as a philosophical doctrine falls victim to the verificationist criterion of meaning. Thus Carnap, in his 1928 Pseudoproblems in Philosophy, categorically states: “In the realism controversy, science can take neither an affirmative nor a negative position since the question has no meaning” (Carnap [1928a] 1968: 333). And Schlick, in his essay “Positivism and Realism” from 1932, points out that realism has no place in science because “the ‘problem of the reality of the external world’ is a meaningless pseudo-problem” (Schlick [1932] 1979: 263). It is interesting to see that realism, in both cases, is explicitly confronted with science. Therefore, it seems to follow that a scientific realist position is anathema for the logical empiricists.

However, it must be seen that the logical empiricist critique of metaphysics was primarily directed against the global positing of an ‘external world.’ As early as in 1926, Schlick argued against this sort of metaphysical conception in the following way:

It is not possible to formulate conceptually, or express in words, what existence or reality properly are. Criteria can of course be given, whereby we distinguish in science and daily life between the ‘really existent’ and the merely ‘illusory’ – but the question about the reality of the external world notoriously involves more than that. Yet whatever this ‘more’ may really be, which we have in mind when attributing existence to the external world, it is at all events wholly inexpressible. We have nothing against anyone attaching meaning to such a question, but must insist with all emphasis that this cannot be stated.

(Schlick [1926] 1979: 100)

Moreover, in his 1931 lecture “The Future of Philosophy,” given at the Seventh International Congress of Philosophy in Oxford, Schlick pointed out:

Any cognition we can have of ‘Being,’ of the inmost nature of things, is gained entirely by the special sciences; they are the true ontology, and there can be no other. Each true scientific proposition expresses in some way the real nature of things – if it did not, it would simply not be true. So in regard to metaphysics the justification of our view is that it explains the vanity of all metaphysical efforts which has shown itself in the hopeless variety of systems all struggling against each other. Most of the so-called metaphysical propositions are no propositions at all, but meaningless combinations of words; and the rest are not ‘metaphysical’ at all, they are simply concealed scientific statements the truth or falsehood of which can be ascertained by the ordinary methods of experience and observation.

(Schlick [1931] 2008: 301–302)

Thus according to the logical empiricist point of view, there is no place for a realistic metaphysics within our theoretical account of the world. It is empirical science by which questions of ontology are answered. Consequently, ‘scientific philosophy,’ as conceived of by the logical empiricists, turns out as a form of naturalism.¹

It is a well-known fact that there existed a further variant of metaphysics that was criticized especially by Carnap. As Carnap points out in his Der logische Aufbau der Welt, the term ‘metaphysics’ is used by some philosophers “for the result of a nonrational, purely intuitive process” (Carnap [1928b] 1968: 295). Carnap refers the reader to the writings of Henri Bergson and claims that “[i]n referring metaphysics to the area of the nonrational, we are in agreement with many metaphysicians” (ibid.). However, in his famous 1932 critique of Martin Heidegger’s philosophy of ‘Being,’ Carnap rejected the nonrational variant of metaphysics as completely meaningless. (There is much more to be said about this aspect of the logical empiricist critique of metaphysics, but that would require an essay of its own.)²

Coming back to the logical empiricist critique of the realist ‘external world’ metaphysics, it is important to note that this critique was directed not only against a particular philosophical system but also against the views of certain contemporary scientists, especially physicists. Thus, for instance, Schlick argued in his “Positivism and Realism” that those physicists who postulate an external world ‘behind’ the world of observable phenomena are on the wrong metaphysical track (cf. Schlick [1932] 1979: sect. III). One must see in this connection that Schlick’s argument was an implicit critique of his teacher Max Planck, who in “Positivismus und reale Außenwelt” rejected the positivist doctrine of Ernst Mach (rather aggressively) in favor of a ‘realist’ position according to which the external world must be presupposed in order to identify the causes of the very appearance and behavior of observable phenomena (see Planck [1931] 1932: esp. p. 82). Schlick commented on this as follows:

However we may twist and turn, it is impossible to interpret a reality-statement otherwise than as fitting into a perceptual context. It is absolutely the same kind of reality that we have to attribute to the data of consciousness and to physical events. Scarcely anything in the history of philosophy has created more confusion than the attempt to pick out one of the two as true ‘being.’ Wherever the term ‘real’ is intelligibly used, it has one and the same meaning.

(Schlick [1932] 1979: 276)

Accordingly, for Schlick the theoretically postulated entities of physics, for example electrons, do not have the status of transcendent ‘things-in-themselves.’ They rather form part of Kantian empirical reality. In Schlick’s own words:

In order to settle the dispute about realism, it is of the greatest importance to alert the physicist to the fact that his external world is nothing else but the nature which also surrounds us in daily life, and is not the ‘transcendent world’ of the metaphysicians. The difference between the two is […] quite particularly evident in the philosophy of Kant. Nature, and everything of which the physicist can and must speak, belongs, in Kant’s view, to empirical reality, and the meaning of this […] is explained by him exactly as we have also had to do. Atoms, in Kant’s system, have no transcendent reality – they are not ‘things-in-themselves.’ Thus the physicist cannot appeal to the Kantian philosophy; his arguments lead only to the empirical external world that we all acknowledge, not to a transcendent one; his electrons are not metaphysical entities.

(Schlick [1932] 1979: 278)

It must be kept in mind that by ‘empirical reality’ Schlick meant the whole realm of verifiable – and at the same time regular – perceptual connections. It is for this reason that he claimed that logical positivism (or what he alternatively called “coherent empiricism”) and empirical realism are compatible with each other. Everyone accepting the principle of verification, Schlick proclaimed, “must actually be an empirical realist” (Schlick[1932] 1979: 283).³

3 Three varieties of ‘empirical’ realism

3.1 Reichenbach’s probabilistic realism

Carnap, Schlick, and the other members of the Vienna Circle were not the only representatives of the logical empiricist movement. There was also the so-called Berlin Group around Hans Reichenbach.⁴ However, it was Reichenbach himself who drew a sharp distinction between both groups, reserving the term ‘logistic empiricism’ for the Berlin group while characterizing the stance defended by the Viennese group, especially by Carnap in his Der logische Aufbau der Welt, as ‘logistic positivism.’⁵ Thus in his article “Logistic Empiricism in Germany and the Present State of Its Proponents,” Reichenbach states:

The tautological character of the positivistic system […] could not justify the predictive character of science. The system, in its seductive symmetry, lacked one essential quality: it did not correspond to the meanings of propositions, as these are expressed in the practice of science. It could not develop a theory of propositions about the future.

(Reichenbach 1936: 152)

And Reichenbach pointedly continues:

This was the precise reason why the Berlin group could not accept positivism. The members of this circle insisted upon the necessity of a theory of propositions about the future. They maintained that any philosophy which neglected the fact and function of propositions about the future in science flagrantly contradicted the very first condition of empiricism: viz., to correspond to the practice of science.

(ibid.)

As Reichenbach had already complained in his 1931 review of Carnap’s Aufbau (see Reichen-bach 1931), the Viennese – ‘positivistic’ – conception suffered from a systematic neglect of the inductive part of scientific theory construction. Verification by observable events and facts alone would not suffice in order to account for the “practice of science.” Rather, the prediction of as yet unobserved events and facts is, what according to Reichenbach, defines the central aim of science. But exactly this precludes the task of ultimate verification. Or, as Reichenbach put it in his 1936 article, “propositions about the future can not be expressed to state certain truths” (Reichenbach 1936: 153). Rather, a (non-symmetric) “probability-logic” (154) must be established by which it becomes possible to “apply the laws and concepts of probability to reality” (156).

It was in his seminal Experience and Prediction from 1938 that Reichenbach systematically worked out this sort of probabilistic approach toward reality.⁶ His framework for designing the intended probabilistic and at the same time realist point of view was the theory of meaning, that is, semantics. What he proposed was what he called a “probability theory of meaning” (see Reichenbach 1938: §7), which he thought was strong enough to incorporate a semantics for theoretical terms, such as ‘atom,’ ‘electromagnetic field,’ or what have you (see ibid., §25). Reichenbach’s crucial point in this connection was the assumption of a surplus meaning of theoretical terms: the meaning of theoretical terms, according to Reichenbach, is not exhausted by their being reducible to an observational evidence base. However, exactly this was implied by the Vienna Circle’s verificationist criterion of meaning. More exactly speaking, this criterion demanded that the whole realm of ‘indirect’ theoretical statements (containing theoretical terms) be converted into ‘direct’ observation statements (or so-called protocol-sentences).⁷ That is, a...

Table of contents

• Cover
• Title
• Copyright
• CONTENTS
• List of contributors
• Introduction: scientific realism in the 21st century
• PART I Historical development of the realist stance
• PART II Classic debate: core issues and positions
• PART III Perspectives on contemporary debates
• PART IV The realism debate in disciplinary context
• PART V Broader reflections
• Index