difference in the accidents and events of our lives. It is, however, much more common in discourses concerning abstract matters, where the terms stand for collections of other terms, sometimes at the pleasure of the speaker or writer, than in the common and necessary affairs of life. For here frequent use, and the constancy of the phænomena of nature, intended to be expressed by words, have rendered their sense determinate and certain. However, it seems possible, and even not very difficult, for two truly candid and intelligent persons to understand each other upon any subject.
That we may enter more particularly into the causes of this confusion, and consequently be the better enabled to prevent it, let us consider words according to the four classes above-mentioned.
Now mistakes will happen in the words of the first class, viz. such as have ideas only, where the persons have associated these words with different impressions. And the method to rectify any mistake of this kind is for each person to shew with what actual impressions he has associated the word in question. But mistakes here are not common.
In words of the second class, viz. such as have both ideas and definitions, it often happens, that one person’s knowledge is much more full than another’s, and, consequently, his idea and definition much more extensive. This must cause a misapprehension on one side, which yet may easily be rectified by recurring to the definition. It happens also sometimes in words of this class, that a man’s ideas, i.e. the miniatures excited in his nervous system by the word, are not always suitable to his definition, i.e. are not the same with those which the words of the definition would excite. If then this person should pretend, or even design, to reason from his definition, and yet reason from his idea, a misapprehension will arise in the hearer, who supposes him to reason from his definition merely.
In words of the third class, which have definitions only, and no immediate ideas, mistakes generally arise through want of fixed definitions mutually acknowledged, and kept to. However, as imperfect fluctuating ideas, that have little relation to the definitions, are often apt to adhere to the words of this class, mistakes must arise from this cause also.
As to the words of the fourth class, or those which have neither ideas nor definitions, it is easy to ascertain their use by inserting them in sentences, whose import is known and acknowledged; this being the method in which children learn to decypher them: so that mistakes could not arise in the words of this class, did we use moderate care and candour. And, indeed, since children learn the uses of words most evidently without having any data, any fixed point at all, it is to be hoped, that philosophers, and candid persons, may learn at last to understand one another with facility and certainty; and get to the very bottom of the connexion between words and ideas.
