In this blog post, we will examine various philosophical criteria for distinguishing between science and non-science and explore whether parapsychology can be recognized as a science.
Parapsychology is the study of supernatural psychological phenomena related to psychic abilities, the spiritual world, spiritual beings, and spiritual powers. Despite not being recognized as a science for a long time, parapsychology was officially acknowledged in 1969 when the American Association for the Advancement of Science approved the Parapsychological Association as an affiliate organization.
However, many scientists consider parapsychology to be pseudoscience and were dissatisfied with this decision. So, can parapsychology be considered a science? Before answering this question, we need to consider what science is. The problem of distinguishing between science and non-science is called the demarcation problem in the philosophy of science. This demarcation problem is a major theme in the philosophy of science and was first explored by E. Mach,
J. H. Poincaré, and P. Duhem, and later became the subject of research by logical positivists such as L. Wittgenstein, M. Schlick, R. Carnap, and H. Reichenbach. Additionally, this problem was a major concern in Karl Popper’s methodological reflection on science. Philosophers of science have proposed various criteria for distinguishing science from non-science. Early logical positivists argued for the criterion of “verifiability,” while later logical positivists and logical empiricists explained this as “confirmability.”
Popper pointed out the problems with these criteria and proposed “falsifiability” as a new criterion. However, Popper’s criterion was also criticized by scholars of “new philosophy of science” such as T. S. Kuhn, N. R. Hanson, and P. K. Feyerabend.
This essay criticizes the criteria of logical positivism, logical empiricism, and falsificationism from the perspective of “new philosophy of science,” criticizes the criteria for demarcation proposed in the philosophy of science, and seeks improvements for resolving the demarcation problem.
First, logical positivism can be seen as a combination of the positivism of Comte and Mill and 20th-century modern logic. Logical positivists accept Mach’s position that modern science is based on direct experience and that scientific theories are inductively derived from observational data. They hold a phenomenalist position that scientific inquiry must begin with objective observational data and be expressed in a neutral observational language independent of all theories. Logical positivists viewed scientific theories as “deductive systems of scientific propositions” and believed that only scientific propositions have meaning. Therefore, for them, the distinction between science and non-science was equivalent to the distinction between meaningful and meaningless propositions, and the criterion of meaningfulness was considered the criterion for distinguishing between science and non-science.
They asserted the principle of verification as the criterion of meaningfulness and used verifiability as the criterion for distinguishing between science and non-science. For a proposition to be considered meaningful, it must be verifiable. Based on this criterion, logical positivists attempted to distinguish between scientific propositions and meaningless propositions, but ultimately, only recorded propositions or observational propositions that could be directly verified by current perception remained as verifiable propositions. As a result, not only metaphysical propositions but also various propositions in value philosophy, ethics, aesthetics, and other fields were regarded as meaningless and unscientific. Ultimately, logical positivists abandoned the criterion of decisive verifiability.
Logical empiricists, who emerged after logical positivism, proposed a weakened criterion of “confirmability” instead of decisive verifiability. Confirmability holds that a proposition has meaning if it can be confirmed to some extent. Logical empiricists analyzed the confirmability relationship between scientific laws and observational sentences that confirm or refute them in order to explain the formation of meaning in scientific concepts.
According to the criterion of confirmability, a proposition is considered to have meaning if it can be confirmed with empirical probability. For example, the law of universal gravitation and the laws of thermodynamics can be confirmed as universal propositions under specific conditions. According to this criterion, propositions about the past and future are also considered meaningful through inductive reasoning and observation of others’ actions. However, metaphysical propositions remain meaningless. This criterion of confirmability attempted to resolve the problems faced by the criterion of verifiability in logical positivism but encountered the logical problem of the “paradox of confirmation.” For example, if we have the hypothesis that “all crows are black,” then white swans, which are not crows, would also confirm this hypothesis. This raises doubts about the validity of the criterion of confirmability.
Popper criticized the criteria of meaningfulness in logical positivism and logical empiricism as unsuitable for distinguishing between science and non-science, and proposed a new criterion of falsifiability. He argued that verification and confirmation cannot secure logical validity based on inductive science, and proposed falsifiability as the criterion for distinguishing pure science from non-science. Popper argued that for a scientific proposition to be recognized as scientific, it must be falsifiable. According to his criterion, it is not meaningless but metaphysical or pseudoscientific elements that distinguish non-science, and the criterion of falsifiability is based on the rules of the scientific method (problems, new theories, deduction of propositions, attempts at refutation, and competition between theories).
Although Popper’s criterion of falsifiability is seen as an alternative solution to the problems of logical positivism and logical empiricism, the bias toward understanding scientific observation and science solely from a logical perspective remains. This point has been criticized by Kuhn and Feyerabend.
After criticizing the criteria for distinguishing between logic positivism, logical empiricism, and falsificationism, we can conclude that none of them are perfect criteria for distinguishing between science and non-science. They share three common problems. First, they presuppose the existence of pure observation and neutrality independent of scientific theories. Second, they attempt to reduce science to inductive or deductive rules. Third, they assume that scientific discovery and justification can be distinguished. These issues have left the demarcation problem unresolved and continue to spark new debates. However, the criteria for demarcation proposed by demarcation theorists have not merely remained as subjects of debate. They have evolved into attempts to resolve the demarcation problem not only from a methodological perspective but also through a historical perspective.
