It must not, however, be supposed that in popular use the connotation of any word is invariable.  Logicians have attempted to classify terms into Univocal (having only one meaning) and AEquivocal (or ambiguous); and no doubt some words (like ‘civil,’ ‘natural,’ ‘proud,’ ‘liberal,’ ‘humorous’) are more manifestly liable to ambiguous use than some others.  But in truth all general terms are popularly and classically used in somewhat different senses.

Figurative or tropical language chiefly consists in the transfer of words to new senses, as by metaphor or metonymy.  In the course of years, too, words change their meanings; and before the time of Dryden our whole vocabulary was much more fluid and adaptable than it has since become.  Such authors as Bacon, Milton, and Sir Thomas Browne often used words derived from the Latin in some sense they originally had in Latin, though in English they had acquired another meaning.  Spenser and Shakespeare, besides this practice, sometimes use words in a way that can only be justified by their choosing to have it so; whilst their contemporaries, Beaumont and Fletcher, write the perfect modern language, as Dryden observed.  Lapse of time, however, is not the chief cause of variation in the sense of words.  The matters which terms are used to denote are often so complicated or so refined in the assemblage, interfusion, or gradation of their qualities, that terms do not exist in sufficient abundance and discriminativeness to denote the things and, at the same time, to convey by connotation a determinate sense of their agreements and differences.  In discussing politics, religion, ethics, aesthetics, this imperfection of language is continually felt; and the only escape from it, short of coining new words, is to use such words as we have, now in one sense, now in another somewhat different, and to trust to the context, or to the resources of the literary art, in order to convey the true meaning.  Against this evil the having been born since Dryden is no protection.  It behoves us, then, to remember that terms are not classifiable into Univocal and AEquivocal, but that all terms are susceptible of being used aequivocally, and that honesty and lucidity require us to try, as well as we can, to use each term univocally in the same context.

The context of any proposition always proceeds upon some assumption or understanding as to the scope of the discussion, which controls the interpretation of every statement and of every word.  This was called by De Morgan the “universe of discourse”:  an older name for it, revived by Dr. Venn, and surely a better one, is suppositio.  If we are talking of children, and ‘play’ is mentioned, the suppositio limits the suggestiveness of the word in one way; whilst if Monaco is the subject of conversation, the same word ‘play,’ under the influence of a different suppositio, excites altogether different ideas.  Hence to ignore the suppositio is a great source of fallacies