Correlate - correlative - correlation
The words correlate, correlative, and correlation are used in different ways in different contexts, but all the uses involve the idea of a relation between two (or more) items or classes of item. What distinguishes the different uses are the different kinds of relation and the different kinds of items between which the relation holds.
- A correlation may be a relation of correspondence between two sets of items (or, in more technical language, between the values of two variables), the items between which the relation holds being events, states of affairs, characteristics of objects, etc. For example, there is a correlation between the state of the weather and sales of ice-cream – the warmer the weather, the more ice cream is sold, i.e., there is a correspondence between a rise in temperature and a rise in the sale of ice cream. Clearly many scientific laws state correlations between two sets of items, e.g., Boyle’s law, according to which, temperature remaining constant, the pressure of a given quantity of gas varies inversely with its volume, i.e., the greater the pressure of the gas, the smaller its volume. Correlations of this kind, which are established empirically, by scientific experiment, sociological survey, casual observation, etc., may be described as positive when, as in the first example, a rise in one variable corresponds to a rise in the other; or negative when, as with Boyle’s Law, a rise in one variable corresponds to a fall in the other. (N.B. the variables between which these correlations hold are usually referred to as correlates rather than as correlatives.)
- Two words or concepts are correlative (and each of them is the (or a) correlative of the other) when there is a reciprocal or complementary relationship between them, i.e., when a statement involving the first implies a statement involving the second, and conversely. For example, the concepts of cause and effect – the statement ‘X is the cause of Y’ implies the statement ‘Y is the effect of X’, and conversely. Similarly ‘day’ and ‘night’ are correlatives – ‘It is day’ implies ‘It is not night’ and ‘It is night’ implies ‘It is not day’. More contentiously, philosophers have sometimes argued that rights and duties are correlative concepts, that wherever there is a right, there is also a duty, and conversely (as when, e.g., the patient’s right to medical treatment is a correlative of the doctor’s duty to provide it). Clearly, correlations of this kind rest on conceptual considerations or the meanings of words: they are not established empirically, by scientific experiment or sociological survey.
- In the study of grammar two words are said to be correlative(s) when there is a certain kind of co-operative relation between them, viz., when both occur in the same sentence, though not necessarily side by side, and together fulfil a single function. For example, the pair ‘either ... or’ (as in the sentence ‘He is either stupid or insane’) serves to indicate that one of two alternative possibilities must be true; the pair ‘neither ... nor’ (as in ‘She is neither very rich nor very poor’) serves to exclude both of two possibilities; and the pair ‘so ... that’ (as in ‘The weather was so bad that the match was cancelled’) serves to show that the state of affairs referred to in the subordinate ‘that’-clause (the cancellation of the match) was a consequence of the state of affairs referred to in the main clause (the badness of the weather). Other correlatives of this kind are ‘both ... and’, ‘hardly ... when’, ‘if ... then’, ‘less ... than’, ‘more ... than’.
- Note on pronunciation: Correlate, which may be either a verb, a noun, or an adjective, is always pronounced with the stress on the first syllable, IPA: / 'kɒ rɪ (or ə) ˌlert/; correlative, which may be either an adjective or a noun, is pronounced with the stress on the second syllable, IPA: / kɒ 'rɛ lə tɪv/; and correlation, which is always a noun, is pronounced with the stress on the third syllable, IPA: / ˌkəʊ (or ɒ) rɪ 'ler ʃən/.