Logical Positivism

Roger Trigg. Encyclopedia of Science and Religion. Editor: J Wentzel Vrede van Huyssteen. Volume 2, Macmillan Reference USA, 2003.

The term logical positivism is particularly associated with the so-called Vienna Circle, a group of leading philosophers, mathematicians, and scientists that met in Vienna, Austria, in the late 1920s and early 1930s, with German philosopher Moritz Schlick (1882-1936) as chairman. They put forward what they regarded as a “scientific world-conception,” which was both anticlerical and opposed to metaphysics. It was, they believed, characterized by two main features. The first was a general empiricism, and the second a devotion to a certain rigorous way of thinking that they called logical analysis. This relied particularly on the techniques of modern formal logic.

Empiricism, in the tradition of such philosophers as David Hume (1711-1776), holds that knowledge can only be obtained from direct experience. Although explicitly a science-based philosophy, it always causes problems for science because science always wishes to generalize from present experience through induction. A strict empiricism will, however, wish to deduce all claims to knowledge from the direct experience of which we are infallibly aware. Knowledge is the product of our pooled, intersubjective experience. What is beyond the reach of human perception and observation cannot be judged to be real. In its effects, the view becomes centered on human judgment and dependent on human capabilities. It is anthropocentric in that it will only deal with what exists in so far as it is accessible to human experience. The latter is defined in terms of what is “immediately given.” In other words, what is in principle beyond the reach of the human senses cannot be meaningfully discussed. Science defines what it is possible to know, and a strict empiricism sets the limits, as the manifesto for the Vienna Circle puts it, “for the content of legitimate knowledge” (p. 309).

The Circle held that “the meaning of every statement of science must be statable by reduction to a statement about the given” (p. 309). This puts the whole of science (and hence, they believed, of knowledge) on a firm empirical footing. It is, however, worth noting that, even at the time, it was questionable whether this gave an adequate account of physics. Modern quantum mechanics has been plagued by disputes about the status of subatomic particles. These disputes often themselves stem from positivist views about the dependence of knowledge on sense experience. The difficulty is how far we can posit entities that by definition we cannot observe. Can they be thought really to exist even though they cannot be directly observed? That these kinds of questions were major stumbling blocks can be illustrated by considering that for logical positivists even the issue of the other side of the moon was a problem before humans had actually observed it. They could only say that it could be observed “in principle,” and indeed it was eventually observed by humans. There are, however, many items to which modern physics wishes to refer that cannot be observed even in principle, unless those words are stretched beyond any recognizable use. What of the other side of the universe, or the interior of a black hole, not to mention quarks and other subatomic particles?

The Influence of the Vienna Circle

The fame and influence of the Vienna Circle began to be felt in the 1930’s. Such eminent figures as philosophers Rudolf Carnap (1891-1970), Herbert Feigl (1902-1988), and Friedrich Waismann (1896-1959), mathematician Kurt Gödel (1906-1978), and sociologist and economist Otto Neurath (1882-1945) were members, and their own individual influence was spread as they were all scattered across the globe as a result of the political upheavals of the 1930’s in Central Europe, leading up to the Second World War. Other well-known figures were associated in some ways with the Circle. They tended to see Ludwig Wittgenstein (1889-1951) as one of their own, although, particularly in his later philosophy, he reacted very much against the idea that only science could set the standard for knowledge. Philosopher Karl Popper (1902-1993) also betrays some of the influence of the Circle, not least by arguing that the test for science was its ability to test empirically its theories by seeing if they could be falsified. This was a variation on the Circle’s insistence of being able to test scientific theories through empirical verification. His argument was that conclusive verification was impossible to achieve. One can never know that all members of a class have been seen. For example, it is better policy to try to refute the theory that all swans are white than to seek to confirm it. A single black swan will be enough to falsify the theory. Popper’s philosophy of science is therefore geared to making conjectures and attempting to refute them, rather than trying to confirm them. The result inevitably implies a certain agnosticism about scientific truth. Theories always have to be tested for possible falsehood. Yet we cannot know that they are true but only that they have so far survived scrutiny.

V. O. Quine. Two other philosophers attended the meetings of the Circle and were influenced by its outlook. W. V. O. Quine (1908-2000) was one of the leading American philosophers of the twentieth century and put forward a science-based philosophy. He was, however, also influenced by American pragmatism and criticised some of the Vienna Circle’s basic tenets. In particular, it was held that all statements were either synthetic(subject to empirical checking and verification) or analytic (true by definition or by virtue of the meanings of the words used). An example of a synthetic statement would be, “All swans are white.” One can discover there are black swans. Analytic statements would include, “All bachelors are unmarried” and “Two and two are four.” One could not discover either statement to be false by looking at the world. Quine, however, challenged the whole analytic-synthetic distinction, and in so doing, undermined much of its empiricism. He also made space for theoretical entities, such as electrons, which might not be cashed out wholly in empirical terms. He did, however, continue in the belief, strongly held by the Circle, that philosophy was to be subordinated to science, and that there was no room for metaphysics, which could justify the practice of science in the first place.

J. Ayer. The other major philosopher who attended meetings of the Circle was A. J. Ayer (1910-1989). He became the voice of logical positivismin the English-speaking world through the publication of his influential Language, Truth and Logic. First published in 1936 as the first book of a young man, it argued that meaningful statements were to be divided into the two categories of the analytic and synthetic. Any other category of statement had to be dismissed as meaningless. He thus dismissed all metaphysics, and that explicitly included religious statements about God. Genuine statements of fact had to be empirically verifiable. Nothing could be factually significant to people unless they knew how to verify the proposition it purports to express. This was the criterion of verifiablity or the verification principle.

Since the existence of God is not a mere tautology (true by definition), according to Ayer, it could only be a factual statement with empirical consequences. His argument can be illustrated by the way he deals with the suggestion that the occurrence of regularities in nature could be evidence for the existence of God. Yet, according to Ayer, if the claim that there is a god amounts empirically to no more than the claim that certain types of phenomena occur in certain sequences, then talking of God is equivalent to talking of those regularities. Ayer could not allow reference to anything beyond our experience. Speaking of the transcendent, like the metaphysical, was just so much hot air, not a genuine assertion of anything. A parallel might be the claim that there is a heffalump in the garden. If a person said there was a heffalump, but did not know what a heffalump looked like, or indeed how to ever recognise a heffalump, it becomes difficult to know what one is saying. Talking of something that is in principle unverifiable becomes perilously like not saying anything at all.

What went for religion also applied to other wide categories of apparent statements, such as those of ethics and aesthetics. They are not scientifically verifiable and therefore cannot be regarded as saying anything that could be true or false. It has already been remarked that even contemporary physics may want to refer to what lies beyond possible human observation, so the verification principle is a blunt instrument even in science. It was commonly seen, though, to get into most trouble when people questioned the status of the verification principle itself. If one states that the only meaningful statements are those that can be empirically verified, or that all metaphysical claims are literally nonsense, how can one empirically verify those assertions? Is not the basic claim itself meaningless because it is beyond the scope of empirical observation? Ayer’s later claim was that the verifiability criterion was “an axiom,” but particular axioms do not have to be chosen. If someone sees that the adoption of such a rule, or starting point, involved the jettisoning of much that is deemed important in human life, that might seem a good reason for not having the axiom in the first place.

Positivism and the Status of Science

Despite its shortcomings, Ayer’s verification principle, and the veneration for science expressed by the repudiation of metaphysics, had a profound affect on theology and the philosophy of religion for many years in the middle of the twentieth century. In many ways, logical positivism still casts its shadow. The idea that religion is not entitled to talk of realities beyond human experience is a seductive one. Yet it strikes at the root of any belief that the physical world is not all that there is, but that there is another nonmaterial realm. Even within theology, there is a constant temptation to reduce talk of a nonmaterial, transcendent realm, such as the Kingdom of Heaven, to matters of everyday experience. It is still often thought that what cannot ultimately be cashed out in empirical terms cannot refer to anything real. This involves changing our concentration from, say, the reality of God, to issues concerning human reactions, attitudes, and practices. Yet in the end, this is an old-fashioned materialism in a sophisticated guise. It is no different from Thomas Hobbes (1588-1679), the seventeenth-century philosopher, saying that there is no difference between God speaking to someone in a dream and dreaming that God spoke.

In the debate about the relations between science and religion, the legacy of logical positivism is to accord science a philosophical status that is denied metaphysics in general and theology in particular. The tendency will be to assume that the assertions of science have an epistemological priority that theology must always respect. In any dispute science must always be given priority. Yet, logical positivism was an anthropocentric view. It related everything to actual and possible sense experience, which had to be human sense experience. We could not understand claims of radically different kinds of experience. By definition, therefore, it was related to human understanding, and the possibilities of human knowledge. This, though, is different from issues concerning the nature of reality. Science is always human science, but it purports to be about a reality that goes beyond, or transcends, our limited and provisional understanding. Philosophy, and metaphysics in particular, has to recognise these limitations. We have to accept that what exists and how we can know it, are radically different kinds of question. This is the difference between ontology and epistemology. The mistake of the Vienna Circle and those it has influenced is to reduce references to what exists to talk of how we can find it out, when who “we” are is not always clearly defined. Any exaggerated respect for science never makes it clear whether it is upholding present science, or science as it one day could be. Yet the latter idea itself begins to seem highly metaphysical in the sense that it outstrips any possible method of verification at present available to us.

Logical positivism represents the extreme version of the respect for science that permeates contemporary thinking. Yet the status of science is itself an issue of major philosophical concern that cannot be taken for granted. Not least is the fact that science has to assume the existence of an ordered and regular world. This is a resupposition of science. We may as a matter of fact experience nature as uniform, but why is this? Why do humans have the ability, through reason, to understand the innermost workings of the physical world? Why is mathematics somehow applicable to the workings of nature? For logical positivism, questions like these were insoluble, and therefore meaningless in the first place. Yet the worst way of dealing with awkward questions is to pretend that they do not exist on the grounds that they are meaningless.