 Royce’s project was framed as one fundamentally concerned with action as he observed in a 1906 paper. “[T]he fundamental logical relations,” he wrote, “are characteristic not only of our world of thought, but also of our world of action. For will-acts involve acceptance and refusal, affirmation and negation, a consciousness of consequences, a facing of alternatives, a union of various acts in one act; so that the logic of action is in form precisely the same as the logic of abstract thought” (1906, 100). From this perspective, Royce observed in an unpublished lecture from 1905, “There is a fundamental relation which may be called the logical relation par excellence. It is the relation between ‘yes’ and ‘no’, the relation which characterizes two mutually exclusive alternatives, that together exhaust all the possibilities. It is the relation that one faces, when one has a choice to make. It is also the relation that obtains between any logical class and the negative of that class” (1905a, 6). The \(O\)-relation then marks both necessity and possibility (that is, it marks a necessary relation between ‘yes’ and ‘no’ and it exhausts the possibilities). As I observed earlier, the \(O\)-relation can be captured in modern modal logic by representing it as the conjunction of two conditionals such that \(O(A\: B)\) is \(\Box (A \equiv \neg B)\). Although not founded as a modal logic, system \(\Sigma\) is modal in its operations and so potentially formalizable in modal terms.