deductive system
21Outline of logic — The following outline is provided as an overview of and topical guide to logic: Logic – formal science of using reason, considered a branch of both philosophy and mathematics. Logic investigates and classifies the structure of statements and… …
22Theory (mathematical logic) — This article is about theories in a formal language, as studied in mathematical logic. For other uses, see Theory (disambiguation). In mathematical logic, a theory (also called a formal theory) is a set of sentences in a formal language. Usually… …
23Logic — For other uses, see Logic (disambiguation). Philosophy …
24Soundness — In mathematical logic, a logical system has the soundness property if and only if its inference rules prove only formulas that are valid with respect to its semantics. In most cases, this comes down to its rules having the property of preserving… …
25Metalogic — is the study of the metatheory of logic. While logic is the study of the manner in which logical systems can be used to decide the correctness of arguments, metalogic studies the properties of the logical systems themselves.[1] According to… …
26Argument — This article is about the subject as it is studied in logic and philosophy. For other uses, see Argument (disambiguation). In philosophy and logic, an argument is an attempt to persuade someone of something, by giving reasons or evidence for… …
27metaphysics — /met euh fiz iks/, n. (used with a sing. v.) 1. the branch of philosophy that treats of first principles, includes ontology and cosmology, and is intimately connected with epistemology. 2. philosophy, esp. in its more abstruse branches. 3. the… …
28Spinoza: metaphysics and knowledge — G.H.R.Parkinson The philosophical writings of Spinoza are notoriously obscure, and they have been interpreted in many ways. Some interpreters see Spinoza as (in the words of a contemporary)1 ‘the reformer of the new [sc. Cartesian] philosophy’.… …
29Aristotle — For other uses, see Aristotle (disambiguation). Ἀριστοτέλης, Aristotélēs Marble bust of Aristotle. Roman copy after a Gree …
30Fallacy — In logic and rhetoric, a fallacy is usually incorrect argumentation in reasoning resulting in a misconception or presumption. By accident or design, fallacies may exploit emotional triggers in the listener or interlocutor (appeal to emotion), or… …
