Demarcation problem

The demarcation problem, also called Demarkationsproblem asks in the philosophy of science Karl Popper after a criterion that allegations ( sets, set systems ) can be distinguished from statements of empirical science of logic, mathematics, metaphysics, or even of myths. Popper proposes to select the falsifiability of a statement by basis sets as a criterion of demarcation.

According to Popper, David Hume had already handled the problem, but only by Immanuel Kant, the question of the limits of scientific knowledge was placed at the center: " ... what and how much can reason and understanding, free from all experience, recognize, ...". Popper suggested therefore originally the name " Kant cal problem " before. However, he emphasized later that the boundaries of empirical science does not constitute the limits of reasonable and rational debatable. Already Aristotle, however, had one criterion specified, then the empirical science, the time- variable, non-empirical sciences such as mathematics, however, treated the immutable.

Falsifiability / refutability

Main article: falsificationism

For Karl Popper 's Hume's " problem of induction " the question of the validity of the laws of nature. It was created by the apparent contradiction between the " basic thesis of empiricism ": Only experience can teach us about the truth or falsity of a fact statement.

Popper suggested to solve the questions, to drop the implicit assumption that sentences must be fully decidable. He sees instead the laws of nature as theories as " teilentscheidbar ," that is not verifiable, however, falsifiable by empirical facts and thus open to criticism. In early versions time, he was wearing a very radical modification of Einstein's dictum before ( that equated the theoretically recordable reality with the falsifiable, a position which he later so not represented ):

"Insofar as the theorems of a science refer to reality, they must be falsifiable, and thus they are not falsifiable, they do not refer to reality. "

As a result of Popper as a criterion for distinguishing the falsifiability of an assertion by empirical facts.

" An empirical- scientific system must be able to fail because of the experience."

The falsifiability criterion has first to do with the logical structure of statements ( how can they fail logically ), and 2 with their methodological use patterns ( how they can be made ​​to fail because of the experience).

Popper's demarcation problem is not to be confused with the previously discussed his time in Vienna Circle problem, which goes back to Wittgenstein, namely: how to distinguish meaningful sentences of nonsense is ( " verification criterion of meaning ").

By Popper's solution to the issues of induction and the definition has the following consequences: 1 Metaphysical statements can not be explained from the outset to be meaningless. Second laws of nature are, because neither verifiable nor falsifiable finally, nothing more than conjecture knowledge: they form strictly speaking not a "system of our knowledge ", but a " system of hypotheses ."

The criterion for determining when a theory is scientific experience or empirical content has (that is, when they make a scientific statement about reality ), has established itself outside of the developed Popper's critical rationalism, even if only partially and in more or less modified form.

In analytical philosophy emerges as Widerlegbarkeitskriterium. A thesis, which in principle can not be falsified, is considered not scientific, since it makes no verifiable by empirical observation statements or no falsifiable predictions true. Therefore, any analytical result and any empirical findings can be interpreted as evidence to confirm such a hypothesis.

The establishment of falsifiability as a central criterion for scientific means that hypotheses and theories must be testable always. If falsification is not possible, there is foreclosure, ie immunization against alternative viewpoints and contradictory facts. However does not mean each experimental refutation of a scientific theory must be abandoned. So may be questionable about the methodological correctness of an experiment. It is also possible to introduce supporting hypotheses that protect a theory. Example: To determine the orbit of Uranus, astronomers turned to Newton's law of gravitation. However, the observations were contrary to expectations. Now instead consider Newton's law refuted, they formed the ad hoc hypothesis that there must be another, as yet unknown planet, which later was confirmed. By introducing ad hoc hypotheses of falsifiability of an empirical statement is reduced. Popper suggested therefore L.Sc.D. the rule, to refrain entirely on ad hoc hypotheses. The philosopher of science Imre Lakatos, however, took the view that a theory (or a research program ) only as " degenerate " and thus to be regarded as unscientific when it is refuted in practice at every significant test.

Other Demarkationskriterien

In addition to the criterion of falsifiability, other criteria are proposed to demarcate science from non-science in the philosophy of science, so by the induction positivism and verification. For Martin Gardner confirmation of a theory by evidence and expertise of researchers are crucial. Paul R. Thargard suggests the presence of factors theory, research community and historical context is to demarcationcriterion. The historian of science Thomas Kuhn Samuel emphasized the progress in terms of a progression of different phases. He refused Poppers proposal of falsifiability for demarcation and reached only to demand concrete predictions on. Instead of falsifiability, he suggested the possibility of development as a criterion of demarcation. Within a theory it must be possible to operate normal science, ie to solve minor problems within the chosen paradigm ( " puzzle-solving "). In non- scientific teaching is just not possible this improvement. "They had rules to apply, They had no puzzles to solve and THEREFORE no science to practice. " Imre Lakatos sees the progressiveness of a research program as the key criterion.

Requirements for empirical statements

The criteria ( target values ​​), to meet the statements of empirical science, are led by different currents of philosophy of science: