To define a thing, says Dr. Watts, we must ascertain with what it agrees, then note the most remarkable attribute of difference, and join the two together.
Probity—the disposition to acknowledge the rights of mankind.
Justice—the disposition to maintain the rights of mankind.
Benevolence—the disposition to improve the rights of mankind.
Deceit—the concealed violation of the rights of mankind.
Injustice—the open violation of the rights of mankind.
Malevolence—hatred of the rights of mankind.
In defining a word we seek some class to which to refer it, that we may identify it, and fix attention upon that peculiarity by which we can distinguish it from all other things. 'Probity and 'justice' are referred to 'disposition,' with reference to the 'rights of mankind' as their sphere of existence: and acknowledgment, and maintenance, are mentioned as the distinguishing features.
Distinctions must not be made without differences. The definition should be plainer than the thing defined. Aristotle's definition of motion is considered defective in this respect:—'Motion—an act of a being in power, so far forth as it is in power.' Tautological definitions cause more to be supposed than is true—the too terse explanation leaves some necessary thing unmentioned. A perfect definition requires the union of the concise, the clear, and the adequate. Some persons are so unskilful in the analysis of terms as to occasion the advice Nil explicare—never explain yourself if you wish to be understood.
Double meanings should be avoided. The writer may himself alternate in their use, and the reader may take the word in the unintended meaning. All men have not the strong sense of Johnson. When Caleb Whiteford inquired seriously of the Doctor, whether he really considered that a man ought to be transported, like Barrington, the pickpocket, for being guilty of a double meaning. 'Sir,' said Johnson, 'if a man means well, the more he means the better'—which, whether real or fictitious, is one of the happiest answers that ever crushed a quibble.*