Saul Aaron Kripke was an American analytic philosopher and logician. He was Distinguished Professor of Philosophy at the Graduate Center of the City University of New York and emeritus professor at Princeton University. From the 1960s until his death,he was a central figure in a number of fields related to mathematical and modal logic,philosophy of language and mathematics,metaphysics,epistemology,and recursion theory.
In natural languages,an indicative conditional is a conditional sentence such as "If Leona is at home,she isn't in Paris",whose grammatical form restricts it to discussing what could be true. Indicatives are typically defined in opposition to counterfactual conditionals,which have extra grammatical marking which allows them to discuss eventualities which are no longer possible.
David Kellogg Lewis was an American philosopher. Lewis taught briefly at UCLA and then at Princeton University from 1970 until his death. He is closely associated with Australia,whose philosophical community he visited almost annually for more than 30 years.
Jerry Alan Fodor was an American philosopher and the author of many crucial works in the fields of philosophy of mind and cognitive science. His writings in these fields laid the groundwork for the modularity of mind and the language of thought hypotheses,and he is recognized as having had "an enormous influence on virtually every portion of the philosophy of mind literature since 1960." At the time of his death in 2017,he held the position of State of New Jersey Professor of Philosophy,Emeritus,at Rutgers University,and had taught previously at the City University of New York Graduate Center and MIT.
Counterfactual conditionals are conditional sentences which discuss what would have been true under different circumstances,e.g. "If Peter believed in ghosts,he would be afraid to be here." Counterfactuals are contrasted with indicatives,which are generally restricted to discussing open possibilities. Counterfactuals are characterized grammatically by their use of fake tense morphology,which some languages use in combination with other kinds of morphology including aspect and mood.
Nicholas Rescher was a German-born American philosopher,polymath,and author,who was a professor of philosophy at the University of Pittsburgh from 1961. He was chairman of the Center for Philosophy of Science and chairman of the philosophy department.
In logic,a strict conditional is a conditional governed by a modal operator,that is,a logical connective of modal logic. It is logically equivalent to the material conditional of classical logic,combined with the necessity operator from modal logic. For any two propositions p and q,the formula p →q says that p materially implies q while says that p strictly implies q. Strict conditionals are the result of Clarence Irving Lewis's attempt to find a conditional for logic that can adequately express indicative conditionals in natural language. They have also been used in studying Molinist theology.
A possible world is a complete and consistent way the world is or could have been. Possible worlds are widely used as a formal device in logic,philosophy,and linguistics in order to provide a semantics for intensional and modal logic. Their metaphysical status has been a subject of controversy in philosophy,with modal realists such as David Lewis arguing that they are literally existing alternate realities,and others such as Robert Stalnaker arguing that they are not.
Dorothy Margaret Doig Edgington FBA is a philosopher active in metaphysics and philosophical logic. She is particularly known for her work on the logic of conditionals and vagueness.
Modal realism is the view propounded by philosopher David Lewis that all possible worlds are real in the same way as is the actual world:they are "of a kind with this world of ours." It is based on four tenets:possible worlds exist,possible worlds are not different in kind from the actual world,possible worlds are irreducible entities,and the term actual in actual world is indexical,i.e. any subject can declare their world to be the actual one,much as they label the place they are "here" and the time they are "now".
Gilbert Harman was an American philosopher,who taught at Princeton University from 1963 until his retirement in 2017. He published widely in philosophy of language,cognitive science,philosophy of mind,ethics,moral psychology,epistemology,statistical learning theory,and metaphysics. He and George Miller co-directed the Princeton University Cognitive Science Laboratory. Harman taught or co-taught courses in Electrical Engineering,Computer Science,Psychology,Philosophy,and Linguistics.
In philosophical logic,the concept of an impossible world is used to model certain phenomena that cannot be adequately handled using ordinary possible worlds. An impossible world,,is the same sort of thing as a possible world ,except that it is in some sense "impossible." Depending on the context,this may mean that some contradictions,statements of the form are true at ,or that the normal laws of logic,metaphysics,and mathematics,fail to hold at ,or both. Impossible worlds are controversial objects in philosophy,logic,and semantics. They have been around since the advent of possible world semantics for modal logic,as well as world based semantics for non-classical logics,but have yet to find the ubiquitous acceptance,that their possible counterparts have found in all walks of philosophy.
Stephen Roy Albert Neale is a British philosopher and specialist in the philosophy of language who has written extensively about meaning,information,interpretation,and communication,and more generally about issues at the intersection of philosophy and linguistics. Neale is a Distinguished Professor of Philosophy and Linguistics and holder of the John H. Kornblith Family Chair in the Philosophy of Science and Values at the Graduate Center,City University of New York (CUNY).
In philosophy—more specifically,in its sub-fields semantics,semiotics,philosophy of language,metaphysics,and metasemantics—meaning "is a relationship between two sorts of things:signs and the kinds of things they intend,express,or signify".
William G. Lycan is an American philosopher and professor emeritus at University of North Carolina at Chapel Hill,where he was formerly the William Rand Kenan,Jr. Distinguished Professor. Since 2011,Lycan is also distinguished visiting professor of philosophy at the University of Connecticut,where he continues to research,teach,and advise graduate students.
Two-dimensionalism is an approach to semantics in analytic philosophy. It is a theory of how to determine the sense and reference of a word and the truth-value of a sentence. It is intended to resolve the puzzle:How is it possible to discover empirically that a necessary truth is true? Two-dimensionalism provides an analysis of the semantics of words and sentences that makes sense of this possibility. The theory was first developed by Robert Stalnaker,but it has been advocated by numerous philosophers since,including David Chalmers.
John L. Pollock (1940–2009) was an American philosopher known for influential work in epistemology,philosophical logic,cognitive science,and artificial intelligence.
Formal semantics is the study of grammatical meaning in natural languages using formal concepts from logic,mathematics and theoretical computer science. It is an interdisciplinary field,sometimes regarded as a subfield of both linguistics and philosophy of language. It provides accounts of what linguistic expressions mean and how their meanings are composed from the meanings of their parts. The enterprise of formal semantics can be thought of as that of reverse-engineering the semantic components of natural languages' grammars.
In philosophy,similarity or resemblance is a relation between objects that constitutes how much these objects are alike. Similarity comes in degrees:e.g. oranges are more similar to apples than to the moon. It is traditionally seen as an internal relation and analyzed in terms of shared properties:two things are similar because they have a property in common. The more properties they share,the more similar they are. They resemble each other exactly if they share all their properties. So an orange is similar to the moon because they both share the property of being round,but it is even more similar to an apple because additionally,they both share various other properties,like the property of being a fruit. On a formal level,similarity is usually considered to be a relation that is reflexive (everything resembles itself),symmetric (if a is similar to b then b is similar to a) and non-transitive (a need not resemble c despite a resembling b and b resembling c). Similarity comes in two forms:respective similarity,which is relative to one respect or feature,and overall similarity,which expresses the degree of resemblance between two objects all things considered. There is no general consensus whether similarity is an objective,mind-independent feature of reality,and,if so,whether it is a fundamental feature or reducible to other features. Resemblance is central to human cognition since it provides the basis for the categorization of entities into kinds and for various other cognitive processes like analogical reasoning. Similarity has played a central role in various philosophical theories,e.g. as a solution to the problem of universals through resemblance nominalism or in the analysis of counterfactuals in terms of similarity between possible worlds.
In propositional logic,import-export is a name given to the propositional form of Exportation:
