Non-classical logic

<p>Non-classical logics (and sometimes alternative logics or non-Aristotelian logics) are <a href="/facts/Formal_system/KaeDAjK7">formal systems</a> that differ in a significant way from <a href="/facts/Classical_logic/ls62MAms">standard logical systems</a> such as <a href="/facts/Propositional_logic/MNt5v31V">propositional</a> and <a href="/facts/Predicate_logic/lcISqWIg">predicate</a> logic. There are several ways in which this is commonly the case, including by way of extensions, deviations, and variations. The aim of these departures is to make it possible to construct different models of <a href="/facts/Logical_consequence/AyDXp4dn">logical consequence</a> and <a href="/facts/Logical_truth/N0bUYhUW">logical truth</a>.
</p><p><a href="/facts/Philosophical_logic/Ld8lnKDA">Philosophical logic</a> is understood to encompass and focus on non-classical logics, although the term has other meanings as well. In addition, some parts of <a href="/facts/Theoretical_computer_science/jSkGGuvy">theoretical computer science</a> can be thought of as using non-classical reasoning, although this varies according to the subject area. For example, the basic <a href="/facts/Boolean_algebra/VkCToAmg">boolean</a> functions (e.g. <a href="/facts/Logical_conjunction/62uyyn1d">AND</a>, <a href="/facts/Logical_disjunction/jbI2EGlM">OR</a>, <a href="/facts/Negation/q5AQBvBj">NOT</a>, etc) in <a href="/facts/Computer_science/lN3pEyPz">computer science</a> are very much <a href="/facts/Classical_logic/ls62MAms">classical</a> in nature, as is clearly the case given that they can be fully described by classical <a href="/facts/Truth_table/4KsmArDW">truth tables</a>. However, in contrast, some <a href="/facts/Automated_theorem_proving/vKGvuKFI">computerized proof methods</a> may not use classical logic in the reasoning process.
</p>

Non-classical logic open-in-new

Non-classical logic