C. S. Peirce Manuscripts

πλ 1 Prolegomena to an Apology for Pragmatism

Come, reader, let us construct a diagram to illustrate the general course of thought. "Why do that when the thought itself is present to us?" Such, substantially, has been the objection raised by more than one or two superior intelligences, among them by an eminent General. Recluse that I am I was not ready with the counter-question, which should have been, "General, you make of use of maps during a campaign, I believe. Why do you so, when the country they represent is right there?" Thereupon, had he replied, that he found details in the maps that were not "right there", but were in the enemy's lines, I should have pressed the question, " Am I to understand, then, that if you were thoroughly and perfectly familiar [...]

πλ 2

with the country, no man of it would ever be of the slightest use to you in laying out your detailed plans? To that he must have rejoined, "I do not say that because I might wish to stick in pins in order to trace out and study the daily changes of the situations." To that, again, my surrejoinder should have been, "Well, General, that precisely corresponds to the advantage of a diagram of the course of thought. Indeed, just there is the advantage of diagrams in general. Namely, one can make exact experiments upon diagrams, and look out for unintended change thereby brought about in the relations of different parts of the diagram to one another. These operations in reasoning take the place of the experiments upon real things that one performs in chemical and physical research. Chemists have sometimes described