In an argument, the premises form a representation of the conclusion, because they indicate the interpretant of the argument, or representation representing it to represent its object. The premises may afford a likeness, index, or symbol of the conclusion. In deductive argument, the conclusion is represented by the premises as by a general sign under which it is contained. In hypotheses, something like the conclusion is proved, that is, the premises form a likeness of the conclusion. [—]
That it is different with induction another example will show.

    SI, SII, SIII, and SIV are taken as samples of the collection M;
    SI, SII, SIII, and SIV are P:
    .·. All M is P.

Hence the first premise amounts to saying that “SI, SII, SIII, and SIV” is an index of M. Hence the premises are an index of the conclusion.