What led Peirce to these cosmological speculations at that time can only be surmised. Although it is clear that many of the roots of Peirce’s grand idea ran deep into the earliest layers of his thought, it does seem that after his marriage to Juliette in 1883, and after he found out that his career at Johns Hopkins had been lost, he became decidedly focused on the riddle of the universe.33 In his outline of how the argument of his book had developed (sel. 23, pp. 175–176), he noted that after he had turned his illuminating categories to “the domain of natural selection,” he had been “irresistibly carried on to speculations concerning physics”: “One bold saltus landed me in a garden of fruitful and beautiful suggestions….” That “bold saltus” may have been the “guess” itself, perhaps as expressed in his January 1884 “Design and Chance” lecture to the Johns Hopkins Metaphysical Club: “Now I will suppose that all known laws are due to chance and repose upon others far less rigid themselves due to chance and so on in an infinite regress … and in this way we see the possibility of an indefinite approximation toward a complete explanation of nature…. May not the laws of physics be habits gradually acquired by systems.” For three or four years following his Metaphysical Club lecture, Peirce roamed in his Epicurean “garden of fruitful and beautiful suggestions”:—his “One, Two, Three” writings of 1885–86 were part of that exploration. By the fall of 1887, as he began writing “A Guess at the Riddle,” Peirce’s initial exploration had worked itself out and he had started looking for further implications or illuminations of his guess for sociology and theology.34 The final two chapters, projected but probably never written, were to be expositions of the triad in those two subjects.
Another possibility is that the “bold saltus” was the “leap” he took, probably in the summer of 1885, from his growing understanding of the usefulness of his categories for logic to the speculation that they provided the key to a rich and unified system of science. By fall 1885 at the latest, he could show how “the whole organism of logic may be mentally evolved from the three conceptions of first, second, and third.” He would conclude that “if these three conceptions enter as we find they do as elements of all conceptions connected with reasoning, they must be virtually in the mind when reasoning first commences” and he would add that “in that sense, they must be innate ideas” and “there must be in consciousness three faculties corresponding to these three categories” (W5:245) which, in turn, “must be capable of a physiological explanation from three fundamental properties of the nervous system” (W5:247). It was Peirce’s conjecture that his categories, firstness, secondness, and thirdness, or perhaps even the underlying conceptions “one,” “two,” and “three,” were the building blocks for a vast, integrated system of knowledge, that led him by mid-1886 to turn the evolutionary speculation of his “Design and Chance” lecture into his guess at the riddle of the universe, namely, that the universe may be understood as a process in which chance brings forth first, or original, events, which, because of an inherent tendency “to acquire determinate properties, to take habits,” become more and more systematic and law governed. The evolving law produces seconds and the tendency to take habits, which generates law, is the third “or mediating element” between firsts and seconds (W5:293). By early 1888, when he sketched chapter seven for “A Guess at the Riddle” (sel. 28), he had refined his guess to this succinct statement: “three elements are active in the world, first, chance; second, law; and third, habit-taking.”
The main thrust of “A Guess at the Riddle” was an exploration of the fecundity of Peirce’s categories for different sciences and the construction of a unifying structure of fundamental conceptions. In each of the extant chapter sketches Peirce used his categories as a device for rethinking and refining old ideas. For example, in chapter 1, “Trichotomy” (sel. 23), he showed how ubiquitous firstness, secondness, and thirdness are by connecting them with common conceptions such as spontaneity, result, and bridge, or beginning, end, and process. But why stop with one, two, three, he asked. Because, he said, “any number, however large, can be built out of triads; and consequently no idea can be involved in such a number radically different from the idea of three.” He used a model of a road with three-way forkings to demonstrate his point. Peirce’s analysis of degenerate categories revealed that there are two distinct varieties of secondness, one internal and one external. It may have been Hegel’s failure to understand this, Peirce suggested, that led him to commit “the trifling oversight of forgetting that there is a real world with real actions and reactions.”
Chapter 2, “The Triad in Reasoning,” was probably never written, unless Peirce intended “One, Two, Three: Fundamental Categories of Thought and of Nature” (W5: sel. 35) to be a preliminary draft, or at least a precursor of it. However, it is very suggestively outlined in the “Contents” (sel. 22) with particular reference to Peirce’s 1885 paper in the American Journal of Mathematics (W5: sel. 30) where it was stressed that for “a perfect system of logical notation” it is necessary to employ three kinds of signs: icons, indices, and tokens (what would later be called “symbols”). Immediately following “A Guess at the Riddle” is a short selection on Steele MacKaye’s theory of dramatic expression entitled “Trichotomic” (sel. 29). This paper, probably written for oral presentation during the early part of 1888 while “Guess” was in progress, effectively though very briefly summarizes four of its chapters (1, 2, 4, and 5). The discussion of signs complements the outline given in the “Contents” (sel. 22), and, together, they give a good idea of what Peirce had in mind for Chapter 2.
Chapter 3, “The Triad in Metaphysics,” (sel. 24) is only a fragment of a sketch of what Peirce planned to write, but it strongly indicates that Peirce viewed his cosmology in relation to Greek thought, particularly pre-Socratic philosophy His plan was to “run over all the conceptions that played an important part in the pre-Socratic philosophy and see how far they can be expressed in terms of one, two, three.” He did not get far, but he pointed out that the Greek arche, the “primal matter out of which the world [was] made,” was quintessentially his first. A fragmentary list of pre-Socratic doctrines (annotation 181.4–5), probably to be used as a source-list for Chapter 3, indicates further some of what Peirce might have included had he completed that chapter. For example, the thirtieth item on this list is a quotation of Parmenides taken from Plato’s Symposium (178b): “He devised Love the very first of all the gods.” Peirce then remarked: “But this doctrine was of course infinitely more ancient. Hesiod, quoted by Plato in the same place in the Symposium, puts Chaos first, earth second, and love third.”
In Chapter 4, “The Triad in Psychology” (sel. 25), the application of his categories revealed to Peirce that there are “three radically different elements of consciousness”: immediate feeling (consciousness of the first), polar sense (consciousness of the second), and synthetical consciousness (consciousness of a third or medium). In Chapter 5, “The Triad in Physiology” (sel. 26), Peirce used his categories to find a threefold division in the physiology of the nervous system that would account for the three kinds of consciousness. As though anticipating that he might be accused of reductionism, Peirce wrote: “No materialism is implied in this, further than that intimate dependence of the action of the mind upon the body, which every student of the subject must and does now acknowledge” (p. 188). Peirce concluded that three fundamental functions of the nervous