Logical Positivism

Logical positivism is the perspective on knowledge that only verifiable statements are meaningful and valuable. It emerged in the 1930s when a group of philosophers, sociologists, and scientists known as the Vienna Circle tried to update empiricism with advances in logic. Empiricism is the idea that we acquire knowledge through our senses. The positivists were heavily influenced by one of the founders of sociology, Auguste Comte, who charted the progression of human inquiry through three stages: the religious, the metaphysical, and the scientific. The early work of philosopher Ludwig Wittgenstein was also an important inspiration for the logical positivists. He argued that since language represented the world, it must somehow mirror the world. According to him, if we investigate the logic of language, we could thereby learn about the logic of the world. Although most philosophers consider logical positivism a failed philosophy, it continues to be very influential, especially in the scientific community.

Background

The Vienna Circle included philosopher Rudolf Carnap, who many consider to have written the manifesto of logical positivism, The Logical Structure of the World, in 1928. The sociologist Otto Neurath, who invented many of the signs that direct traffic in cities and airports, was also a member. Other members included physicist Moritz Schlick and philosopher A. J. Ayer. The Vienna Circle wanted to get rid of a priori judgments about the world, which means they wanted to get rid of assumptions and stick to the facts. The logical positivists considered science to be a body of statements about the world. They sought to classify and organize these statements to focus on meaningful results and clarify what should count as knowledge and what should not. They did this using three principles.

Overview

The most important principle was the verification principle. For a statement to be meaningful, it must be testable. For example, you could test the sentence "Alcohol is poisonous to slugs" by dropping slugs into alcohol. If all the slugs die, you can conclude the sentence has been verified by the procedures of scientific observation. Therefore, it is meaningful. On the other hand, you cannot test the sentence, "We can only prove something exists if nothing also exists." Therefore, it has no meaning in the context of human knowledge. The positivists would classify it as metaphysical and reject it.

The second principle works in tandem with the first. It emphasizes the importance of distinguishing between two types of meaningful sentences: one that is verifiable and one that is logically necessary. This is called the analytic/synthetic distinction, where synthetic refers to the verifiable or testable proposition, and analytic refers to logically necessary statements. Examples of the latter include "6 + 3 = 9" and "All married people have a spouse." Even though logically necessary statements are not strictly testable, they remain meaningful. After all, it is not very practical to ask every single married person on the planet whether they have a spouse.

The third principle relates to the goal of the logical positivists, which was to unite the empirical sciences. They thought that one way to achieve this goal was to reduce theoretical terms to empirical terms. For example, natural selection is a theoretical concept that explains how organisms change over time, according to the theory of evolution. Organisms that adapt to their environment are more likely to pass on their genes to offspring, who inherit the favorable adaptation over multiple generations. These are the theoretical terms of natural selection. A reduction of these to empirical terms would be observations of a white moth species in an industrial city that turned grey over several generations. Because the white ones did not camouflage themselves as well to blend into their sooty and smoggy environment, predators killed them before they could pass on their genes. Theory is an explanation with some evidence, while the empirical terms would constitute all the evidence gathered through observation to support the theory.

Impact

The positivists valued clarity and precision in language. They thought that it was important to make a hypothesis so clear that anyone could understand it and test it. This was crucial for the goal of uniting the empirical sciences because specialists often developed obscure vocabulary that was difficult for outsiders to understand. Defining terms helped remove any ambiguity that might cause misunderstanding. The positivists wanted to unite the sciences and reduce the findings of the social sciences, such as history and economics, to a small range of general principles, such as gravitation in physics. However, they were very critical of theories current in psychology and biology at the time. They regarded physics as the most advanced science, one that should be the model of all the others.

The positivists came under a number of significant attacks that undermined their project. First, the verification principle is itself neither testable nor logically necessary. Second, Carnap himself recognized problems with the principle of reduction. Some statements that he had to admit were scientific could not be reduced fully to empirical terms. Third, a philosopher named Willard Quine pointed out the considerable difficulties of distinguishing between analytical and synthetic judgments in a natural language. He concluded that this cannot be done reliably, and his argument was very influential. Finally, Karl Popper argued that it was not verification that made a statement scientific but rather falsification. He shifted emphasis from the facts to natural laws. Each experiment or study was an opportunity to prove a hypothesis wrong. If it was proven wrong in multiple cases, it could be discarded. If not, then it was retained to guide further experimentation and research. In this way, all the many facts gleaned from observation were reduced to a few over-arching laws.

Logical positivism was a key stage in the development of the philosophy of science, and despite the many criticisms it endured, it continues to exert a strong influence on many people's worldview. The New Atheist movement, as led by biologist Richard Dawkins, owes a debt to the logical positivists. In philosophy, however, it has fallen out of favor almost completely.

While pure logical positivism had fallen out of favor in the twenty-first century, its ideas continued to be applied in areas of scientific and psychological research methods through its use of empirical verification, standardization, evidence-based practices, and emphasis on using clear and precise language. Modern concepts based on logical positivism include post-positivism, critical rationalism, and scientific realism.

Bibliography

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