Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve. -Karl Popper
Scientific theories are formed as a result of observations and a consistent logic that explains those observations. These theories form the basis of scientific knowledge, that is essential in the advancement and development of man. These theories are tested by the aid of experiments that yield results which either verify or disprove the theory in question.
Whether the results corroborate or disprove a given theory is decided by the scientists conducting the experiments, but it falls to the philosophers or epistemologists to ascertain the factors that essentially determine the validity of the experimental data.
This influences the direction taken by the research and the relevance and viability of it. If a theory is supported by validated results, it provides evidence in favor of the theory, but if the data disproves the theory, it is discarded in order to be replaced by a more evolved theory capable of overcoming the limitations of the current theory.
But not every hypotheses can be considered as a scientific theory, this is because not all hypotheses can be physically tested. A scientific theory is that hypothesis that possesses the capability of being proven to be false, i.e. it is falsifiable.
In the event that one does not account for the falsifiability of the theory, a confirmation bias is observed where corroborating evidence is presented while actively ignoring the evidence against that theory, thereby causing the research to be incorrect and also unethical.
Principle of Falsifiability
Karl Popper, an Austrian-British philosopher and professor, proposed this concept. Falsifiability or refutability of a hypothesis or a theory is the inherent ability of it to be proven false, i.e. it is possible to conceptualize and posit a scenario or an observation that can effectually prove that particular claim to be wrong, false, or illogical.
It is defined as, "The logical possibility that an insertion will be shown to be false by a particular observation of a physical experiment."
The main aim of this principle is to attempt to disprove a hypothesis such that falsifiability is synonymous with testability. For a theory to be tested, it is imperative for it to provide at least a theoretical scenario in which it may be proved wrong.
A theory that does not provide such a scenario, is deemed to be unscientific as it makes claims and predictions that cannot be tested. Hence the quality of falsifiability acts as a criterion of demarcation between scientific and non-scientific hypotheses.
He explains it in "The Logic of Scientific Discovery (p.19) as, "My proposal is based upon an asymmetry between verifiability and falsifiability; an asymmetry which results from the logical form of universal statements. For these are never derivable from singular statements, but can be contradicted by singular statements."
He explains that certain theories may be falsifiable either in practice or in principle. The claim that all swans are white can be practically refuted by the sighting of a black swan.
However the claim that there will be an earthquake in a certain area after 500 years, can only be refuted in principle as there is no actual physical evidence against it but a theoretical 50% chance exists for the nonoccurrence of the earthquake.
In the event that a unfalsifiable theory is accepted as a true scientific theory, it is regarded as a part of pseudoscience, and is described by Wolfgang Pauli, an Austrian-born Swiss theoretical physicist, as "it is not only not right, it is not even wrong!"
Therefore, the basic concept of the principle is to demonstrate that no theory is perfect and completely correct, but if it is falsifiable (read "testable"), and the results are found to be in support of the theory, then that theory is accepted as being scientifically and logically sound.
This can be explained by comparing the theories put forth by Isaac Newton and Albert Einstein regarding gravity. Newton's theory has been accepted to be true for many centuries now, due to the fact that it is easily observable and evident in nature and also as it has been supported by substantial amount of accurate experimentation (falsifiable) and research.
However, the theory that was put forth by Einstein made different falsifiable predictions about the gravitational lensing of light. It refers to the ability of strong gravitational fields (large mass) to be able to bend and refocus the trajectory of light.
Einstein's theory not only claimed that the path of light would undergo twice the amount of deflection that Newton's theory predicted, but also claimed that light would slow down as well.
Given that the gravitational field is weak or moderate, both the theories make the same predictions, and hence are both correct. However, since Einstein's theory is a specialized superset of Newton's theory, by the principle of Occam's razor, Einstein's theory is preferred over that of Newton's.
But since the calculation given by Newton's theory are easier and almost accurate, it is used in doing general calculations, but where specificity is required (for GPS coordinates) Einstein's complicated calculations are used.
This demonstrates that a theory may be scientific only if it is falsifiable, and that it holds true only as long as it is not refuted by a more evolved theory or an advanced research technique.
Naive Falsification and Popper's Swan Argument
Karl Popper proposed that two types of assumptions or statements were made by scientists in the formulation of a theory. Singular existential statements asserted the existence or presence of one particular entity.
He explained this by giving the example of swans, i.e. such a statement could be put forth as "there exists an x such that x is a swan, and x is white". The second type of statement was a universal statement, that could be expressed as, "for all x, if x is a swan, then x is white".
However, this did not sufficiently explain how one was to infer a universal statement from a collection of existential statements.
In the case of the swans, this move from existential to universal statement was not possible as it would lead to the deduction that all swans are white, which is logically invalid since black swans do exist in nature, and hence Popper suggested falsifiability as a solution to this conundrum.
He suggested that although the existential statement could not corroborate or help prove the universal statement, it could be used to disprove it, i.e. the singular existential observation of black swans could disprove that all swans were white.
Hence by logical analysis (modus tollens), if one observes a white swan, one can assume that at least one swan is white, leading the researcher to assume that all swans are white, but the observation of a black swan, by the researcher, would disprove this hypothesis.
Problems with the Principle of Falsifiability
❖ Data is generated as a result of experiments based on a compounded theory composed of many individual suppositions (interconnected web). Hence when comparing the data to the parent theory, it proves difficult to point out exactly which theory is being proved or disproved.
❖ When a prediction or a theory is refuted by experimental evidence, it does not always imply that the theory is incorrect. The dissonance of the theory and the data may also be due to technological error or due to an error in the interpretation of the data.
❖ Assumptions about the existence of certain elements cannot be proved to be falsifiable due to the inability or failure in detecting and isolating those elements. For, example, claims of the existence of black holes, DNA, viruses, atoms, photons, electrons, etc, cannot be falsifiable.
❖ Branches of science such as applied science, sociology, anthropology, etc, rely on deducible evidence without testing any hypothesis or theory, hence it is not in accordance with the principle of falsifiability.
❖ The Raven paradox refers to the paradox that arises form the query of what actually can be considered as evidence for a given hypothesis. It highlights the gap between inductive and deductive reasoning.
The theory cannot be falsifiable if all researchers testing it assume different parameters and data while conducting their experiments. The experimental design is flawed from the beginning.
Examples of Falsifiability
❖ Economists of the Austrian School posit that macroeconomics is an empirically unfalsifiable entity, since the only method to appropriately study and understand economic events in the world is by carrying out a detailed and calculated study of the intentions of the individual economic decision-makers, which are based on certain fundamental truths.
Hence, the prediction of such economic events cannot be described as a science.
❖ The existence of fossilized remains of any modern-day animals like the rabbit or hippo could, in effect, disprove evolution. J.B.S. Haldane proposed that evolution could be disproved if one were to find "fossil rabbits from the Precambrian era".
❖ Karl Popper stated that "most mathematical theories are, like those of physics and biology, hypothetico-deductive: pure mathematics therefore turns out to be much closer to the natural sciences whose hypotheses are conjectures, than it seemed even recently."
This implied that the fundamental theories of mathematics along with sciences such as physics and biology were falsifiable, and hence, scientific.
Karl Popper claimed that the criteria behind determining the scientific status of a theory was its refutability, which is affirmed in the words of Albert Einstein:
"No amount of experimentation can ever prove me right; a single experiment can prove me wrong."
"No amount of experimentation can ever prove me right; a single experiment can prove me wrong."