parsimony, principle of

Also called Ockham’s Razor. Principle that one should not multiply entities unnecessarily, or make further assumptions than are needed, and in general that one should pursue the simplest hypothesis. Adoption of this principle, though seemingly obvious, leads to problems about the role of simplicity in science, especially when we are choosing between hypotheses that are

2 Comments

perfection, principle of

Also called the principle of the best. Principle of German philosopher and mathematician Gottfried Wilhelm Leibniz (1646-1716) that the actual world is the best of all possible worlds. Bertrand Russell (1872-1970) argued that Leibniz did not fully distinguish this principle from that of sufficient reason. Source: B Russell, A Critical Exposition of the Philosophy of Leibniz (1900), §§14-15 Perfection is a

1 Comments

plenitude, principle of

Principle that if the universe is to be as perfect as possible it must be as full as possible, in the sense that it contains as many kinds of things as it possibly could contain. The world of nature must be as rich as possible. This is connected with the idea, used by St

8 Comments

pre-established harmony, doctrine of

Doctrine primarily associated with Gottfried Wilhelm Leibniz (1646-1716) that there is no causation in the world but that each event arises when it does because it was pre-programmed to do so by God when the universe began. The doctrine is often illustrated by the image of the two clocks -attributed to Arnold Geulincx (1625-1669) – which keep perfect

2 Comments

reducibility, axiom of

Axiom introduced by English philosopher and mathematician Bertrand Russell (1872-1970) in connection with the ramified theory of types. It says that any higher-order property or proposition can be reduced to an equivalent first-order one. The ramified theory caused difficulties for defining real numbers (using Dedekind sections) and for the process known as mathematical induction (roughly: if a property belongs

1 Comments

relevant alternatives, theory of

Theory used in defending fallibilism against the charge that it leads to skepticism. Where P and Q are propositions, P counts for this purpose as an alternative to Q if it is inconsistent with Q, and counts as a relevant alternative if to know that Q we must also know that not-P. Variant formulations exist, but the

3 Comments

semantics, truth-conditional

A variant of the correspondence theory, and akin to the redundancy theory. It was developed by the Polish logician Alfred Tarski (1902-1983), and applied to language by British philosopher Donald Davidson. (Also see: MONTAGUE GRAMMAR.) Semantic theory for sentences rather than words (also see: LEXICAL SEMANTICS). We know the meaning of a sentence if we know the

1 Comments

speciation, theory of

(18TH CENTURY) Also called geographic speciation, this theory is most often associated with Ernst Mayr (1904- ), an evolutionary biologist at Harvard University (although many other biologists have theorized on the subject). It asserts that new species arise among sexually reproducing organisms because geographic isolation enables a small subgroup to diverge genetically from the

2 Comments

species essentialism

Also called the natural state model of species, this was based on the ideas of Greek philosopher Aristotle (384-322 BC), and applied by Swedish botanist Carolus Linnaeus (1707-1778) and others in their search for the perfect ‘type specimen’ for each species. It is the concept that all members of a species share a common natural state

3 Comments

species, theory of

(Also referred to as the biological species concept, the isolation species concept, the species concept, and the species taxa.) Most often associated with Ernst Mayr (1904- ), an evolutionary biologist at Harvard University (but many other biologists have theorized on the subject before and since). This is the idea that animals and plants can

1 Comments

stimulus-response model

The stimulus–response model is a characterization of a statistical unit (such as a neuron). The model allows the prediction of a quantitative response to a quantitative stimulus, for example one administered by a researcher. In psychology, stimulus response theory concerns forms of classical conditioning in which a stimulus becomes paired response in a subject’s mind.[1] Fields of application Stimulus–response models are applied

1 Comments

sufficient reason, principle of

Principle that there must be a sufficient reason – causal or otherwise – for why whatever exists or occurs does so, and does so in the place, time and manner that it does. The principle goes back to at least the early 5th century BC – being used by Parmenides (see Eleaticism) in his Fragment 8, lines

1 Comments

tropisms, theory of

Proposed by Jacques Loeb (1859-1924), a physiologist and physician who was associated with the Rockefeller Institute in New York. The concept that all the activities of animals and humans are determined by tropisms, just as plant movements are determined by tropisms. Loeb believed that matters of the mind and inner life will ultimately be

3 Comments

truth theory

Semantic concept formalized by the Polish-American mathematician and logician Alfred Tarski (1902-1983), although other thinkers had previously discussed the idea. Truth theory concerns the truth-values of sentence structures in various formal logical languages. Tarski suggested a table by which these values could be determined (although he was less sure about whether the same rules

1 Comments

types, ramified theory of

For the simple theory, which Frank Plumpton Ramsey (1903-1930) separated out from the ramified theory, properties of objects are of type one, properties of type one properties are of type two, and so on. The ramified theory further classifies properties of each type into orders. A first-order type n+1 property is a property of things of type

4 Comments

types, simple theory of

Theory developed by Bertrand Russell (1872-1970) to deal with paradoxes like his paradox of classes: is the class of all classes that are not members of themselves a member of itself? If yes, no; if no, yes. Russell said there is no such class. Classes (and also properties) cannot all be lumped together, but form a hierarchy.

1 Comments

uniformity of nature, principle of the

A claim that may be offered as a grounding for the INDUCTIVE PRINCIPLE, though it is not always distinguished from the principle itself. It may be crudely formulated as ‘Nature is uniform’, or ‘The future will resemble the past’, or – in a more refined version like that given under inductive principle – with

2 Comments

utilitarianism, Bentham’s theory of

Utilitarianism is a family of normative ethical theories that prescribe actions that maximize happiness and well-being for all affected individuals.[1][2] Although different varieties of utilitarianism admit different characterizations, the basic idea behind all of them is to in some sense maximize utility, which is often defined in terms of well-being or related concepts. For instance, Jeremy Bentham, the founder of utilitarianism, described utility as “that property in

1 Comments

catastrophe theory

In mathematics, catastrophe theory is a branch of bifurcation theory in the study of dynamical systems; it is also a particular special case of more general singularity theory in geometry. Bifurcation theory studies and classifies phenomena characterized by sudden shifts in behavior arising from small changes in circumstances, analysing how the qualitative nature of equation solutions depends on the parameters that appear in the equation.

1 Comments

cyclical theory

The cyclical theory refers to a model used by historians Arthur M. Schlesinger Sr. and Arthur M. Schlesinger Jr. to explain the fluctuations in politics throughout American history.[1][2] In this theory, the United States’s national mood alternates between liberalism and conservatism. Each phase has characteristic features, and each phase is self-limiting, generating the other phase. This alternation has repeated itself several times over the history of the United

7 Comments