# Logical Positivism ## [Positivism and Metaphysics](https://metaphysicist.com/history/positivism/) The motto of the information philosopher is "beyond logic and language." Specifically, we must show that logical positivism and logical empiricism, whose attack on metaphysics began as early as Auguste Compte in the early nineteenth century, have done nothing to solve any of the deep problems about the fundamental nature of reality. Positivism is the claim that the only valid source of knowledge is sensory experience, reinforced by logic and mathematics. Together these provide the empirical evidence for science. Some see this as the "naturalizing" of epistemology. Ernst Mach's positivism claimed that science consists entirely of "economic summaries" of the facts (the results of experiments). He rejected theories about unobservable things like Ludwig Boltzmann's atoms, just a few years before Albert Einstein used Boltzmann's work to prove that atoms exist. This "linguistic turn" and naturalizing of epistemology can be traced back to Kant and perhaps even to Descartes.The logical positivism of Bertrand Russell and Ludwig Wittgenstein claims that all valid knowledge is scientific knowledge, though science is often criticized for "reducing" all phenomena to physical or chemical events. The logical positivists may have identified ontology not with the things themselves but what we can say - using concepts and language - about the things themselves. The idea that all knowledge can be described by true statements began with Leibniz's vision of a universal ambiguity-free language based on a new symbol set, a characterica universalis, and a machine-like calculus ratiocinator that would automatically prove all necessary truths, true in "all possible worlds." Gottlob Frege called Leibniz's idea "a system of notation directly appropriate to objects." In the three hundred years since Leibniz had this vision, logical philosophers and linguistic analysts have sought those truths in the form of "truth-functional" propositions and statements formulated in words, but they have failed to find any necessarily "true" connection between words and objects. Frege had an enormous influence on Bertrand Russell, who shared Frege's dream of reducing mathematics, or at least arithmetic, to logic. The great Principia Mathematica of Russell and Alfred North Whitehead was the epitome of that attempt. It failed with the discovery of Russell's Paradox and later Gödel's incompleteness proof. Russell hoped to work with the young Ludwig Wittgenstein to develop the "logical atoms," the simplest propositions, like "red, here, now," upon which more complex statements could be built. He saw the major problems of philosophy as problems of language and logic, that complete understanding of the natural world could be obtained through a complete set of logical propositions. Wittgenstein's Tractatus Logico-Philosophicus was the height of logical positivism - the idea that all knowledge, including all science, can be represented in logically true statements or propositions - and the first hint of its failure, with its dark comments about how little can be said. 4.11 The totality of true propositions is the total natural science (or the totality of the natural sciences). (Tractatus Logico-Philosophicus) Logical positivists and the logical empiricists of the Vienna Circle not only asserted that all knowledge is scientific knowledge derived from experience, i.e., from verifiable observations, they also added the logical analysis of language as the principal tool for solving philosophical problems. They divided statements into those that are reducible to simpler statements about experience and those with no empirical basis. These latter they called "metaphysics" and "meaningless." While language is too slippery and ambiguous to serve as a reliable tool for philosophical analysis, quantitative information, which underlies all language use, is such a tool. Logical positivists and empiricists mistakenly claim that physical theories can be logically deduced (or derived) from the results of experiments. A second flaw in all empiricist thinking since Locke et al. is the mistaken idea that all knowledge is derived from experience, written on the blank slate of our minds, etc. In science, this is the flawed idea that all knowledge is ultimately experimental. To paraphrase Kant and Charles Sanders Peirce, theories without experiments may be empty, but experiments without theories are blind. By contrast, the modern hypothetical-deductive method of science maintains that theories are not the logical (or inductive) consequences of experiments. As Einstein put it, after shaking off his early enthusiasm for Mach's positivistic ideas, theories are "free inventions of the human mind." Theories begin with hypotheses, mere guesses, "fictions" whose value is shown only when they can be confirmed by the results of experiments. Again and again, theories have predicted behaviors in as yet untested physical conditions that have surprised scientists, often suggesting new experiments that have extended the confirmation of theories, which again surprise us. As pure information, scientific knowledge is far beyond the results of experiments alone. ## [Are there any valid arguments against logical positivism?](https://www.quora.com/What-are-some-good-arguments-against-logical-positivism?share=1) Yes. And they were considered so devastating that I’m not aware of any well known philosopher who continued to advocate the philosophical program since their brief spotlight in the early 20th century. Bertrand Russell was the one philosopher to hold onto his brand of logical positivism, which he called “logical atomism”, the longest, but I’m pretty sure he abandoned the logicism condition essential to his earliest views of the “logical” condition. Logical positivism was an early 20th century philosophy program sometimes also more broadly known as logical empiricism. It contained two components, logicism and positivism. The basic idea was that we can express every true proposition as a logical formula whose constituent variables could be verified by observation. But both philosophical components turned out to be demonstrably problematic for different reasons. Logicism was the view that every proposition, in principle, including mathematical ones, could be reduced to logical propositions. The key was finding the right logic, which Russell and Whitehead thought at first they had with their predicate calculus in Principia Mathematica. The predicate calculus in Principia Mathematica became one of the main logical bases for the logical positivism of the Vienna Circle, as well as Russell’s own logical atomism. Two major problems with a logicism based on predicate calculus arose early on, however. Frege first pointed out Russell's paradox. Russell’s paradox demonstrated that predicate calculus wasn’t sufficient to express propositions about sets (including classes and properties). It can’t answer questions like, does the set of all sets include itself? Russell and others acknowledged the problem, with various attempts to resolve it, usually by either adding some ad hoc restrictions on self-reference or some additional theory of types. In the end, it was the Zermelo–Fraenkel set theory which won out among mathematicians and logicians. The ZF set theory, however, is not itself based in logic. It’s an add-on to assist quantifiable types. So it doesn’t support the logicist hypothesis. The second aspect of the philosophical program, the positivism, has more well known criticisms. Positivism has two epistemological components, empiricism and verficationism. The most well-known criticism came from Karl Popper who proposed a radically different view of empirical propositions. Popper was, in a sense, a logicist responding partly to a relevant criticism that logical positivism had ignored Hume’s problem of induction. He also recognized that they were dealing with foundational epistemic problems. His solution was a claim that empirical propositions were not positive verifiable statements and not inductive. They are deductive statements which can only ever be falsified. The idea, held by some still today, is that science can never tell us what is the case, only what is not the case, with the corollary that if a proposition is not empirically falsifiable, at least in principle, it is not an empirical hypothesis. For many, Popper’s falsificationism put the nail in the coffin for logical positivism, saving a sort of more general logical empiricism which allowed for a non-verificationist view of empirical propositions. However, the debate between verificationists and falsificationists about empirical propositions was never entirely resolved and remains one of the open questions in philosophy of science and epistemology. Both views are problematic, making Russell and Popper’s criticism’s of the other’s views one of the most interesting reads in 20th century philosophy. Another problem with positivism developed more slowly going into the late 20th century as the cognitive and neurosciences developed. Russell’s “atoms” were sometimes described as “sense data”. If you think of an electronic sense device, when it gets a positive trigger, it’s active and plugs in the “true” or “positive” value for a variable. Human biology is not that simple. Sensations don’t appear to be processed individually. And positivism contains the sort of naive realism about experience that we find in the direct realism of Aristotle. We now know that it’s not sensations that we experience at all, but rather the neurological response to sensations. Perception is not a direct experience of sensation just as sensation is not a direct experience of external triggers. Sensation is a mitigation of reality through biological stuff, which is then processed by a neurological system before it is presented as a conscious experience. The idea that we can just plug in positive or negative values to variables based on our sense experience seems incredibly naive now. The process of experience is a lot more complex than individual sensations, so much so that the idea of “sense data” is rendered meaningless when applied to biological organisms. The most common argument presented against logical positivism today is the Humean one, probably because it seems to many to be the shortest knock-out argument. Logical positivism, and more generally logical empiricism, cannot account for itself. We can’t prove logical positivism is true based on logical positivism alone. This isn’t really a knock-out argument in my opinion. It depends on contextualizing logical positivism as an epistemically foundational theory, which is was certainly originally intended to be. But we don’t necessarily need to interpret it as foundational. We might interpret it more pragmatically as a useful tool for modelling verifiable empirical propositions. Electronic devices with sensors and logic boards are essentially logical positivist machines. We’re not. As long as we are sensible about that difference, I don’t see a major problem here. We might see some other sort of knowledge, like the reliability argument from epistemological pragmatism, as more foundational. In that respect, if logical positivism works out better than alternatives, we might conclude that it really is more foundational than those alternatives. We might even propose empirical tests weighing the predictive reliability and expressiveness of verificationism versus falsificationism, for example. As long as we’re not making too lofty claims about its uses, most of the criticism of logical positivism fall away as irrelevant. What it failed to do was provide the epistemic foundation for science that it intended, leaving a foundational gap which remains today. But nothing had sufficiently filled in that gap previously. When understood within its historical context, logical positivism came the closest to filling that foundational gap than any of its predecessors. Even though we don’t take its foundational claims seriously today, it left a legacy we still mostly use in the sciences. Historically, it can be viewed as a natural progression from Descartes’ program by trying to produce a mathematically based science, essentially reducing the historical epistemological debate between Platonic rationalism and Aristotlean empiricism to essential components of every empirical proposition by giving the rational and empirical components essential but distinct roles in all empirical knowledge. Russell, logical empiricism, probably also along with pragmatism and common sense realism, saved philosophy, at least western English speaking academic philosophy, from continuing along its irrelevant, esoteric, solipsistic, and often narcissistic path further into the dominant subjective idealism of the 19th century. Arguably, the foundational debates among philosophers, logicians, mathematicians, and scientists, in which logical positivism was a major contender and influence, helped supercharge the unprecedented growth of science and technology in the 20th century. So while there are quite a few good reasons not to subscribe to logical positivism as a program, it’s worth knowing as a tool, and appreciating as an important historical legacy, and even as a turn in the right direction.