In pre-Columbian literature are allusions to land over sea.
Hence there must have been knowledge of such a land.
This brings us face to face with the necessity of supporting premises with facts. To support the first sub-proposition there must be citations from pre-Columbian literature. This is a mere matter of research. One reason for putting this especial proof first is that in supporting it it is possible to begin with facts which cannot be questioned. It is true that the very next step will bring us upon doubtful territory, but we start from firm ground. The moment that the passages are quoted, the possibility occurs to the mind that they may be taken to refer to lands then known, or as the expression of mythical fancies. These objections must be met. An argument can no more pass an unanswered objection than a locomotive can cross a bridge from which a span is missing. Reasons must here be given for connecting with the New World the passages cited. It will be no less important to show the reasons for supposing that the information which the ancient writers possessed of the New World came from the Norsemen. The rest may all be allowed, and yet be held to have no bearing on the thing to be proved, so that this link in the chain must be made strong and evident.
This last point illustrates the sort of questions which are likely to arise in regard to arrangement. Is it well to introduce here the proofs that this knowledge of another continent came from the Norse, or would it be better to wait until the Icelandic Sagas have been spoken of? In the latter case, the parts of the argument may be more closely bound together, and it gives an air of fairness to the whole when the writer is willing to go back a good way in his argument to take up possible objections and answer them. Against this is to be balanced the possibility that the reader may be put into a suspicious state of mind by finding that a doubtful point is passed over, and so be less easily convinced than he otherwise might be. The writer of an argument must consider these things, and upon the good judgment with which he settles such questions much of his success depends.
In this first sub-proposition there is no need of stating formally the syllogism involved, since, if the first or major premise is successfully defended, the rest follows obviously. As a matter of practical arrangement, then, the sub-proposition and its defense might stand in this order:—
1. The discovery of America by the Norsemen is proved by the allusions in pre-Columbian literature to a land over sea.
a. Citation of passages.
b. Proofs that these do not refer to the Eastern Hemisphere.
c. Proofs that they are not mythical allusions.
d. Proofs that they do refer to America.