Falsifiability
Popper emphasized the asymmetry created by the relation of a universal law with basic observation statements[C] and contrasted falsifiability to the intuitively similar concept of verifiability that was then current in logical positivism.
He insisted that, as a logical criterion, his falsifiability is distinct from the related concept "capacity to be proven wrong" discussed in Lakatos's falsificationism.
As a key notion in the separation of science from non-science and pseudoscience, falsifiability has featured prominently in many scientific controversies and applications, even being used as legal precedent.
[E] For example, the falsifiability of Newton's law of gravitation, as defined by Popper, depends purely on the logical relation it has with a statement such as "The brick fell upwards when released".
The capacity to verify the absence of conditions such as a hidden string[U] attached to the brick is also needed for this state of affairs[A] to eventually falsify Newton's law of gravitation.
For example, in their 2019 article Evidence based medicine as science, Vere and Gibson wrote "[falsifiability has] been considered problematic because theories are not simply tested through falsification but in conjunction with auxiliary assumptions and background knowledge.
[T] Popper thought that it was a basic statement that was a potential falsifier for Newton's theory, because the position of the apple at different times can be measured.
Popper's claims on this point are controversial, since Newtonian physics does not deny that there could be forces acting on the apple that are stronger than Earth's gravity.
A corresponding basic statement that acts as a potential falsifier is "In this industrial area, the relative fitness of the white-bodied peppered moth is high."
This is discussed by Dienes in the case of a variation on the Omphalos hypothesis, which, in addition, specifies that God made the creation in this way to test our faith.
[AI] In other words, specific technologies must be provided to make the statements inter-subjectively-verifiable, i.e., so that scientists know what the falsification or its failure actually means.
In his critique of the falsifiability criterion, Maxwell considered the requirement for decisions in the falsification of, both, the emission of neutrinos (see § Dogmatic falsificationism) and the existence of the melting point.
In the 5th and 6th editions of On the Origin of Species, following a suggestion of Alfred Russel Wallace, Darwin used "Survival of the fittest", an expression first coined by Herbert Spencer, as a synonym for "Natural Selection".
[AK] Popper and others said that, if one uses the most widely accepted definition of "fitness" in modern biology (see subsection § Evolution), namely reproductive success itself, the expression "survival of the fittest" is a tautology.
"[AR][AS] Popper's attacks were not directed toward Marxism, or Marx's theories, which were falsifiable, but toward Marxists who he considered to have ignored the falsifications which had happened.
A survey of 303 federal judges conducted in 1998[AT] found that "[P]roblems with the nonfalsifiable nature of an expert's underlying theory and difficulties with an unknown or too-large error rate were cited in less than 2% of cases.
[42] Together with Maxwell, who raised the problems of falsification in the experiment,[41] he was aware that some convention must be adopted to fix what it means to detect or not a neutrino in this probabilistic context.
[59] Inductive logic itself is not precluded, especially not when it is a deductively valid application of Bayes' theorem that is used to evaluate the probabilities of the hypotheses using the observed data and what is assumed about the priors.
[AZ] The experimental falsifiers and falsifications thus depend on decisions made by scientists in view of the currently accepted technology and its associated theory.
[BK] Popper rejected Hume's explanation of induction and proposed his own mechanism: science progresses by trial and error within an evolutionary epistemology.
Hume believed that his psychological induction process follows laws of nature, but, for him, this does not imply the existence of a method of justification based on logical rules.
In particular, Russell once expressed the view that if Hume's problem cannot be solved, “there is no intellectual difference between sanity and insanity”[72] and actually proposed a method of justification.
Therefore, Lakatos urged Popper to find an inductive principle behind the trial and error learning process[BM] and sophisticated falsificationism was his own approach to address this challenge.
[BP][BQ][BR][BS][BT] Popper's philosophy is sometimes said to fail to recognize the Quine-Duhem thesis, which would make it a form of dogmatic falsificationism.
[BP] Feyerabend wrote in "Against Method" that Lakatos's methodology of scientific research programmes is epistemological anarchism in disguise[BQ] and Musgrave made a similar comment.
He always viewed this component as a creative process beyond the explanatory reach of any rational methodology, but yet used to decide which theories should be studied and applied, find good problems and guess useful conjectures.
[BV] Quoting Einstein to support his view, Popper said that this renders obsolete the need for an inductive methodology or logical path to the laws.
As an anecdotal example, in one of his articles Lakatos challenged Popper to show that his theory was falsifiable: he asked "Under what conditions would you give up your demarcation criterion?".
He rejected Lakatos's argument for ad hoc hypothesis, arguing that science would not have progressed without making use of any and all available methods to support new theories.
[89] In their book Fashionable Nonsense (from 1997, published in the UK as Intellectual Impostures) the physicists Alan Sokal and Jean Bricmont criticised falsifiability.
