How will this sentence probably continue? This question confronts every intelligent reader, whether he realizes it or not, when reading the complete sentence. If the mark before “and,” or the absence of a mark, conveys to him no information upon this point, he learns only through a tiresome mental process of ascertaining the correct relation of the words that follow “and” to the words that precede it. This process is one of holding in suspense two or more possible combinations. It is always distractive, and very often ends in a wrong combination. A semicolon before “and” would suggest that the preceding group of words is complete in itself, and is to be followed by a complete and coördinate thought (“and” indicates the coördination) in the proper sense relation with the group that has preceded. It would at once preclude the expectation of an adjective coördinate with “fallacious.”
We may complete the sentence thus:
66-2. Experience is fallacious; and therefore it is difficult for us to form correct judgments based upon experience.
To exhibit at once the sense relation between the two groups of words in the above (the relation of correct judgment to experience), we inserted the word “therefore”; to show that “and” is to be followed by a group grammatically coördinate with what precedes it, and of like form, we used a semicolon.
If the relation between the groups were closer than the relation suggested by the semicolon, but not so close as indicated by the absence of a mark, the comma would logically be the proper mark. It would suggest neither a word to be grouped with “fallacious” nor a clause to be grouped with all that precedes “and.” It would suggest a different development of the sentence. Such development would tie what follows to a part, not to the whole, of what precedes; and, as there are but three words in this sentence preceding the mark, what follows must be tied to one of them, and not to the whole, as in No. 66-2. Two sentences will serve to illustrate the point:
66-3. Experience is fallacious, and may not safely be depended upon in the formation of correct judgment.
66-4. Experience is fallacious, and unreliable as a basis of correct judgment.
In No. 66-3 the comma notifies the reader that another adjective in the and relation to “fallacious,” is not to follow.
In No. 66-4 the comma is used to confine “as a basis of correct judgment” to “unreliable,” thus disconnecting it from “fallacious.” This makes the language say that experience is fallacious in all things, and unreliable only as a basis of correct judgment.
If the reasoning in our discussion on the differentiation of the comma from the semicolon, be correct, it seems to establish a rule that the semicolon is the mark of choice between two clauses, whether joined by a conjunction or not. It is not entirely the length or the character of the groups of words that determines the choice. The liability to make wrong combinations, especially such combinations as are suggested by the apparent meaning of the language, is to be lessened by the mark.