Possible worlds

By Melia, Joseph

The concept of Possible worlds arises most naturally in the study of possibility and necessity. It is relatively uncontroversial that grass might have been red, or (to put ...

Semantics, possible worlds

By Perry, John R.

Possible worlds semantics (PWS) is a family of ideas and methods that have been used to analyse concepts of philosophical interest. PWS was originally focused on the important ...

Nihilism, metaphysical

By Coggins, Geraldine

Metaphysical nihilism is an answer to the question ‘could there have been nothing?’ In recent analytic philosophy this tends to be interpreted as ‘could there have been no ...

Intensional logics

By Garson, James W.

Intensional logics are systems that distinguish an expression’s intension (roughly, its sense or meaning) from its extension (reference, denotation). The purpose of bringing intensions into logic is to ...

Kripke, Saul Aaron (1940–)

Saul Kripke is one of the most influential philosophers to have written on logic, metaphysics, the philosophy of language, and the philosophy of mind in the twentieth century. ...

Modal Epistemology

By Black, Tim

Modal epistemologies maintain that a belief counts as knowledge only if there is an appropriate modal connection between that belief and the facts of the matter that make ...

Modal logic, philosophical issues in

By McKay, Thomas J.

In reasoning we often use words such as ‘necessarily’, ‘possibly’, ‘can’, ‘could’, ‘must’ and so on. For example, if we know that an argument is valid, then we ...

Modal operators

By Schweizer, Paul

Modal logic is principally concerned with the alethic modalities of necessity and possibility, although this branch of logic is applied to a wide range of linguistic and conceptual ...

Gettier problem

By Hetherington, Stephen

Edmund Gettier, in 1963, introduced into philosophy what soon became known as the Gettier problem. It is still with us – frustratingly so for some, intriguingly so for ...

Indicative conditionals

By Jackson, Frank

Examples of indicative conditionals are ‘If it rained, then the match was cancelled’ and ‘If Alex plays, Carlton will win’. The contrast is with subjunctive or counterfactual conditionals, ...

Model theory

By Hodges, Wilfrid

Model theory studies the relations between sentences of a formal language and the interpretations (or ‘structures’) which make these sentences true or false. It offers precise definitions of ...

Kripke, Saul Aaron (1940–)

By Jubien, Michael

Saul Kripke is one of the most important and influential philosophers of the late twentieth century. He is also one of the leading mathematical logicians, having done seminal ...

Counterfactual conditionals

By Doring, Frank

‘If bats were deaf, they would hunt during the day.’ What you have just read is called a ‘counterfactual’ conditional; it is an ‘If…then…’ statement the components of ...

Evil, problem of

By Adams, Marilyn McCord

In this context, ‘evil’ is given the widest possible scope to signify all of life’s minuses. Within this range, philosophers and theologians distinguish ‘moral evils’ such as war, ...

Intensionality and hyperintensionality

By Nolan, Daniel

Roughly speaking, the extension of an expression is what it picks out in our world: an object for a name, a set of objects for a predicate, and ...

Supervenience

By Jago, Mark

Supervenience is a concept developed by philosophers to capture a way in which certain facts, events or properties rely or depend on others in a noncausal way. It ...

Nozick, Robert (1938–2002)

By Wolff, Jonathan

Although Robert Nozick published on an enormous range of topics, he is best known as a political philosopher, and especially for his powerful and entertaining statement of libertarianism. ...

Nozick, Robert (1938–2002)

By Wolff, Jonathan; Blackburn, Simon

Although Robert Nozick published on an enormous range of topics, he is best known as a political philosopher, and especially for his powerful and entertaining statement of libertarianism. ...

Causation

By Cartwright, Nancy

Two opposed viewpoints raise complementary problems about causation. The first is from Hume: watch the child kick the ball. You see the foot touch the ball and the ...

Hare, Richard Mervyn (1919–2002)

By Price, A.W.

R.M. Hare was the creator of the ethical theory called ‘prescriptivism’. This holds that moral statements differ from purely factual ones in prescribing conduct; they differ from simple ...

Logic, philosophy of

By Forbes, Graeme

Philosophy of logic can be roughly characterized as those philosophical topics which have emerged either from the technical development of symbolic (mathematical) logic, or from the motivations that ...

Shakespeare and philosophy

By Newman, Ira

Known for their attention to literary logic in general, philosophers have not usually focused on the works of specific literary writers. Yet unanticipated benefits often come from grounding ...

Lewis, David Kellogg (1941–2001)

By van Inwagen, Peter

David Lewis has made extremely important and influential contributions to many topics in metaphysics, philosophical logic, the philosophy of science, the philosophy of mind, the philosophy of language, ...

Counterpart theory

By Melia, Joseph

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Hintikka, Jaakko (1929–2015)

By Niiniluoto, Ilkka

Jaakko Hintikka was a Finnish philosopher who developed important new methods and systems in mathematical and philosophical logic. Over a distinguished career in universities in Finland and the ...