# counterfactual conditional

﻿
counterfactual conditional
Sometimes known as subjunctive conditionals, although the terms do not exactly coincide. A counterfactual is a conditional of the form ‘if p were to happen q would’, or ‘if p were to have happened q would have happened’, where the supposition of p is contrary to the known fact that not-p . Such assertions are nevertheless useful: ‘if you had broken the bone, the X-ray would have looked different’, or ‘if the reactor were to fail, this mechanism would click in’ are important truths, even when we know that the bone is not broken or are certain that the reactor will not fail. It is arguably distinctive of laws of nature that they yield counterfactuals (‘if the metal were to be heated, it would expand’), whereas accidentally true generalizations may not. It is clear that counterfactuals cannot be represented by the material implication of the propositional calculus, since that conditional comes out true whenever p is false, so there would be no division between true and false counter-factuals.
Although the subjunctive form indicates a counterfactual, in many contexts it does not seem to matter whether we use a subjunctive form, or a simple conditional form: ‘if you run out of water, you will be in trouble’ seems equivalent to ‘if you were to run out of water, you would be in trouble’. In other contexts there is a big difference: ‘if Oswald did not kill Kennedy, someone else did’ is clearly true, whereas ‘if Oswald had not killed Kennedy, somebody else would have’ is most probably false.
The best-known modern treatment of counterfactuals is that of David Lewis, which evaluates them as true or false according to whether q is true in the ‘most similar’ possible worlds to ours in which p is true. The similarity-ranking this approach needs has proved controversial, particularly since it may need to presuppose some notion of the same laws of nature, whereas part of the interest in counterfactuals is that they promise to illuminate that notion. There is a growing awareness that the classification of conditionals is an extremely tricky business, and categorizing them as counterfactual or not may be of limited use.

Philosophy dictionary. . 2011.

### Look at other dictionaries:

• Counterfactual conditional — For other uses, see Counterfactual (disambiguation). A counterfactual conditional, subjunctive conditional, or remote conditional, abbreviated cf, is a conditional (or if then ) statement indicating what would be the case if its antecedent were… …   Wikipedia

• counterfactual — counterfactual, counterfactual conditional A proposition which states what would have followed had the actual sequence of events or circumstances been different. Thus, to claim that the Battle of Alamein altered the outcome of the Second World… …   Dictionary of sociology

• Counterfactual — may refer to: Counterfactual conditional, a grammatical form (which also relates to philosophy and logic) Counterfactual subjunctive, grammatical forms which in English are known as the past and pluperfect forms of the subjunctive mood… …   Wikipedia

• Conditional — may refer to: Causal conditional, if X then Y, where X is a cause of Y Conditional mood (or conditional tense), a verb form in many languages Conditional probability, the probability of an event A given that another event B has occurred… …   Wikipedia

• counterfactual Philosophy — adjective relating to or expressing what has not happened or is not the case. noun a counterfactual conditional statement (e.g. If kangaroos had no tails, they would topple over) …   English new terms dictionary

• Conditional sentence — For the non custodial punishment for a crime in Canada, see conditional sentence (Canada). In grammar, conditional sentences are sentences discussing factual implications or hypothetical situations and their consequences. Languages use a variety… …   Wikipedia

• Conditional perfect — In linguistics, the conditional perfect is the composed (compound) form of the conditional mood. It refers to a hypothetical action in the past, contingent on something else that did not occur in the past. The difference from the present form of… …   Wikipedia

• conditional — Any proposition of the form ‘if p then q ’. The condition hypothesized, p, is called the antecedent of the conditional, and q the consequent. Various kinds of conditional have been distinguished. The weakest is that of material implication,… …   Philosophy dictionary

• counterfactual — 1. adjective /ˌkaʊntɚˈfæktʃuəl,ˌkaʊn.tə(ɹ)ˈfæk.tʃu.əl/ Contrary to the facts; untrue. 2. noun /ˌkaʊntɚˈfæktʃuəl,ˌkaʊn.tə(ɹ)ˈfæk.tʃu.əl/ a) A claim, hypothesis, or other belief that is contrary to the facts. In recent years there has been… …   Wiktionary

• counterfactual — counterfact, n. counterfactually, adv. /kown teuhr fak chooh euhl/, n. Logic. a conditional statement the first clause of which expresses something contrary to fact, as If I had known. [1945 50; COUNTER + FACTUAL] * * * …   Universalium