For Peirce, for a statement to be meaningful, it must have concrete, pragmatic ramifications. He believed that by articulating such a maxim, metaphysical presuppositions could be purged from scientific inquiry, which would be able to function more helpfully. In this respect, Peirce’s pragmatic maxim seems similar to the verification principle later advocated by the logical positivists. This was the early articulation of his epistemological views, however, and he later revised it and renamed it “pragmaticism,” distinguishing it from other forms of pragmatism which he considered too “nominalistic”(Atkin).
In the beginning, Peirce articulated his understanding of pragmatism in terms of three grades of clarity, which he saw as the issue of the rationalist notion of clear and distinct ideas. His pragmatism was thus a synthesis of a kind of empiricism with rationalist understandings of clarity gleaned from Descartes and Leibniz(Atkin).
Peirce identified his own grade of clarity as the third and highest grade. Here are the three grades(Atkin):
1) Unreflective understanding of ordinary, concrete instance. We must have a basic, intuitive understanding of the nature of gravity, for example, in order to navigate the everyday world.
2) Our ordinary understanding of a concept must be refined by providing a propositional definition of the concept. This moves from the particular and concrete to the general and the abstract.
3) Having articulated a formal definition of the concept, we must then understand what sorts of practical or pragmatic bearing it will have on the world. This is the pragmatic maxim. We must come to know what to expect, and what sort of predictions we can make in light of our knowledge of the thing.
It is at this point that Peirce’s theory of language and meaning becomes important. We articulate reality in terms of conditional statements about what sorts of effects we might expect should our object of inquiry come into certain concrete situations. “If such and such an object were placed in such and such a condition, we can expect such and such a set of results.” For Peirce, understanding of such practical implications of an object was essential to a coherent scientific theory. If our theory did not have any practical bearings on reality, then it was essentially meaningless. It is easy to see how comparisons between Peirce’s pragmatism and the later logical positivist understanding of the verification theory of meaning came abou(Atkin)t.
For Peirce, use of the scientific method to take our inquiry to the limits is how we acquire truth. But how do we know which inquiries are worth investigating? This is where the pragmatic maxim comes in. It helps us to decide where to direct our scientific investigations, in order to weed out purely speculative, and therefore, meaningless, inquiries. In terms of degrees, inquiries which are most likely to have the largest effect on our practical lives are those most pursuing(Atkin).
But this leads to an interesting conunudrum, which Peirce explored when he asked about what we would say about the supposed “hardness” of a diamond which was destroyed before its hardness could be tested. Oddly enough, Peirce insisted that we could say whatever we want about this diamond. Since it is not present to test, it would be no more true to say that it is hard than to say that it is soft(Atkin).
In his later work, however, Peirce was displeased with the relativistic direction in which fellow pragmatists James and Schiller had taken pragmatism. Indeed, he changed his opinion on the aforementioned “diamond” question. Instead, later Peirce adopted more of a realist position and said that we could no definitively whether or not the diamond was hard(Atkin). This led to the development of Peirce’s epistemology in explicitly modal terms. He had rejected his earlier epistemologically reductionistic account of modality, according to which necessity refers merely to our knowledge that something must be the case and possibility referring to our not knowing that something must be the case. It is at this point that he rejected his earlier position as nominalistic, and became a realist about possibility(Atkin).
More specifically, he became a realist about subjunctive conditionals. Meaning is determined, for Peirce, in terms of subjunctive conditionals. Instead of using an indicative conditional such as “if I smash this diamond with a hammer, it will not break,” we would say “if we were to smash this diamond with a hammer, it would not break.” This is true of the diamond regardless of whether or not we smash it(Atkin).
It was in his later work that Peirce became more sympathetic to metaphysics. He wanted, however, metaphysics to be scientific(Atkin). He still wanted experience to be an essential component of meaningful sentences, but this time, he broadened the scope of experience to extend beyond immediate sense experience. On the one hand, “real” experience was defined in terms of this concrete, immediate sense experience. “Ideal” experience, on the other hand, refers to formal reasoning of the sort we see among logicians and mathematicians (Atkin).
Atkin, Albert. Charles Sanders Peirce: Pragmatism. Internet Encyclopedia of Philosophy. Retrieved from: http://www.iep.utm.edu/peircepr/