A rule is a lever necessary for putting to work the exclusively human kind of forming and maintaining of patterns – it is "an embodied generalization which to speak loosely but suggestively, tends to make itself true" (Sellars, 1949, 299).
And others felt the necessity to work with still other entities of diverse natures, like, e.
De Saussure and some of the other structuralists criticised it explicitely; however, and this is often not noticed, very strong arguments against it are offered also by the results of the work of some of the most outstanding analytical philosophers.
The lexicographer is an empirical scientist, whose business is the recording of antecedent facts; and if he glosses 'bachelor' as 'unmarried man' it is because of his belief that there is a relation of synonymy between these forms, implicit in general or preferred usage prior to his own work.
We shall do well to digress now into a brief appraisal of the role of definition in formal work.
The definiens may be a faithful paraphrase of the definiendum into the narrower notation, preserving a direct synonymy5b as of antecedent usage; or the definiens may, in the spirit of explication, improve upon the antecedent usage of the definiendum; or finally, the definiendum may be a newly created notation, newly endowed with meaning here and now. In formal and informal work alike, thus, we find that definition -- except in the extreme case of the explicitly conventional introduction of new notation -- hinges on prior relationships of synonymy.
Then what are we so hard at work on right now?
And the examples of many men of the highest genius, who had, in former times, engaged in this inquiry, but, as appeared to me, without success, led me to imagine it to be a work of so much difficulty, that I would not perhaps have ventured on it so soon had I not heard it currently rumored that I had already completed the inquiry.
What is the justification for a feature in a work of art?
Beginning with Frege, who invented the subject, and continuing through Russell, Wittgenstein, Quine, Austin and their successors, right to the present day, there is no branch of philosophy with so much high quality work as the philosophy of language.