Chapter 8 examines the Fifth Way, which argues for God’s existence from natural bodies acting for an end or purpose. After a translation and the premises are given, the chapter explains how the Fifth Way works and its relevant differences from William Paley’s argument from design. There is a look at teleological arguments for God in Aquinas’s other writings. The chapter examines in what sense(s) Aquinas thinks that natural bodies act for an end and also for a certain good. There is a look at his arguments for final causes in nature. Attention is given to why he holds the crucial premise that bodies which lack intelligence, but act for an end, are directed to their end by something with intelligence and understanding of that end. There is a brief discussion of chance, which Aquinas sees as a rival explanation to finality in nature. The chapter closes with the final steps of the Fifth Way where Aquinas appears to see a single guiding intelligent being in the background of nature.

Peirce’s 1890s cosmological speculations were fascinating failures. Their basic idea, that laws require explanation, which could only be by evolution from lawless chaos, was suggested by the success of statistical reasoning in thermodynamics and in Darwinian biology. But the development of that idea was supposed to predict the forms of physical laws not yet discovered, and none of its mutually incompatible developments could do that. In one version, Peirce projected a form of idealism, anti-conceptual and named ’objective’, in which feelings unfelt by any organism are supposed to constitute the material universe; this idealism disappears from later writings. In another version, he projected a ’law of mind’, fundamental to other laws, confused by some commentators with his c.1902 idea of final causation. But such a law and final causation are polar contraries; in showing this, I develop and defend Peirce’s idea of final causation, made use of in Chapter 9.

The modalities – necessity, possibility, and impossibility – are not topics like the existence of God, creation versus eternity, prophecy, divine attributes, or providence whose “secrets” Maimonides investigates in the Guide. They belong instead to the philosophical and logical framework within which these topics are explored. But they are no less perplexing. The modal terms often differ in meaning in different contexts, depending on whether the subject is physics or metaphysics, and for the falasifa and the mutakallimun. Therefore, in order to address any of the central controversies of the Guide, we must first sort out these modal notions, distinguishing the different conceptions in different contexts.