philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...

, verisimilitude (or truthlikeness) is the

notion Notion or Notions may refer to: Software * Notion (music software), a music composition and performance program * Notion (productivity software), a note-taking and project-management program from Notion Labs Inc. * Notion (window manager), the s ...

that some

proposition In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...

s are closer to being

true True most commonly refers to truth, the state of being in congruence with fact or reality. True may also refer to: Places * True, West Virginia, an unincorporated community in the United States * True, Wisconsin, a town in the United States * ...

than other propositions. The problem of verisimilitude is the problem of articulating what it takes for one false

theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be s ...

to be closer to the truth than another false theory. This problem was central to the

Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the cl ...

, largely because Popper was among the first to affirm that truth is the aim of

scientific inquiry Models of scientific inquiry have two functions: first, to provide a descriptive account of ''how'' scientific inquiry is carried out in practice, and second, to provide an explanatory account of ''why'' scientific inquiry succeeds as well as it ap ...

while acknowledging that most of the greatest scientific theories in the

history of science The history of science covers the development of science from ancient times to the present. It encompasses all three major branches of science: natural, social, and formal. Science's earliest roots can be traced to Ancient Egypt and Meso ...

are, strictly speaking, false. If this long string of purportedly false theories is to constitute progress with respect to the goal of truth, then it must be at least possible for one false theory to be closer to the truth than others.

Karl Popper

Popper assumed that scientists are interested in highly informative theories, in part for methodological reasons—the more informative a theory, the easier it is to test, and the greater its predictive power. However, informative power itself is rather easy to propose, and gaining content by sacrificing truths is unwanted. So Popper proposed that closeness to the truth is a function of two factors: truth and content. The more truths that a theory entails (other things being equal) the closer it is to the truth. Intuitively at least, it seems that

Newton Newton most commonly refers to: * Isaac Newton (1642–1726/1727), English scientist * Newton (unit), SI unit of force named after Isaac Newton Newton may also refer to: Arts and entertainment * ''Newton'' (film), a 2017 Indian film * Newton ( ...

's theory of motion entails a good many more truths than does e.g.

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

's theory, despite that both are known to have flaws. Even two true theories can have differing degrees of verisimilitude, depending on how much true information they deliver. For example, the claim "it will rain next Thursday", if true, seems closer to the truth than the true yet logically weaker claim "it will either rain or be sunny next Thursday". Popper's formal definition of verisimilitude was challenged since 1974 by Pavel Tichý, John Henry Harris, and David Miller, who argued that Popper's definition has an

unintended consequence In the social sciences, unintended consequences (sometimes unanticipated consequences or unforeseen consequences) are outcomes of a purposeful action that are not intended or foreseen. The term was popularised in the twentieth century by Ameri ...

: that no false theory can be closer to the truth than another. Popper himself stated: "I accepted the criticism of my definition within minutes of its presentation, wondering why I had not seen the mistake before." This result gave rise to a search for an account of verisimilitude that did not deem progress towards the truth an impossibility.

Post-Popperian theories

Some of the new theories (e.g. those proposed by David Miller and by Theo Kuipers) build on Popper's approach, guided by the notion that truthlikeness is a function of a truth factor and a content factor. Others (e.g. those advanced by in collaboration with , by Mortensen, and by Ken Gemes) are also inspired by Popper's approach but locate what they believe to be the error of Popper's proposal in his overly generous notion of content, or consequence, proposing instead that the consequences that contribute to closeness to truth must be, in a technical sense, "relevant". A different approach (already proposed by Tichý and and developed especially by

Ilkka Niiniluoto Ilkka Maunu Olavi Niiniluoto (born March 12, 1946) is a Finnish philosopher and mathematician, serving as a professor of philosophy at the University of Helsinki since 1981. He is currently on leave from his position, having been appointed as r ...

and Graham Oddie) takes the "likeness" in truthlikeness literally, holding that a proposition's likeness to the truth is a function of the overall likeness to the actual world of the possible worlds in which the proposition would be true. An attempt to use the notion of point-free metric space is proposed by Giangiacomo Gerla. There is currently a debate about whether or to what extent these different approaches to the concept are compatible.

Methodology

Another problem in Popper's theory of verisimilitude is the connection between truthlikeness as the goal of scientific progress, on the one hand, and methodology, on the other hand, as the ways in which we can to some extent ensure that scientific research actually approaches this goal. Popper conceived of his definition as a justification of his own preferred methodology:

falsificationism Falsificationism may refer to: * Critical rationalism, an epistemological philosophy founded by Karl Popper * Three models of scientific progress in "Falsification and the Methodology of Scientific Research Programmes" by Imre Lakatos ** Dogmatic ...

, in the following sense: suppose theory A is closer to the truth than theory B according to Popper's qualitative definition of verisimilitude; in this case, we will (or should, if that definition had been logically sound) have that all true consequences of B (i.e.: all predicted consequences of theory B's mathematical and physical predictions subject to a particular set of initial conditions) are consequences of heoryA ( ssimilarly predicted consequences – i.e., informally, B ≤ A), and that all false consequences of A are consequences of B (in that those set of events deemed impossible by theory A are a subset of those events deemed impossible B, subject to the same initial data conditions for both – i.e., informally, ¬B ≥ ¬A, so that ¬A ≤ ¬B); this means that, if A and B are so related, then it should be the case that all ''known'' false

empirical Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

consequences of A also follow from B, and all ''known'' true empirical consequences of B do follow from A. So, if A were closer to the truth than B, then A should be better

corroborated Corroborating evidence, also referred to as corroboration, is a type of evidence in law. Types and uses Corroborating evidence tends to support a proposition that is already supported by some initial evidence, therefore confirming the propositio ...

than B by any possible amount of

empirical evidence Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

. Lastly, this easy theorem allows interpretation of the fact that A is actually better corroborated than B as a ''corroboration of the hypothesis'' (or 'meta-hypothesis') that A is more verisimilar than B.

References

{{Karl Popper Concepts in aesthetics Concepts in epistemology Concepts in logic Concepts in metaphilosophy Concepts in metaphysics Concepts in the philosophy of mind Concepts in the philosophy of science Epistemological theories Epistemology of science History of logic History of science Karl Popper Metaphysical theories Metaphysics of mind Ontology Philosophical realism Truth

Karl Popper

Post-Popperian theories

Methodology

See also

References