Part Three focuses on Milton's most developed contribution to theology, his attack on the doctrine of the Trinity. In preparation, we compare De Filio with two other chapters, then sketch some wider contexts, before Chapter 9 applies the methods deployed so far to this single outstanding chapter and extends them. Then Chapters 9 and 10 ask the two questions which stand out. How much do we find Milton to rely on a personal, self-advantaging or elliptical method of reasoning? And does the theological thinking of Paradise Lost illuminate, continue, or contrast with this personal staple of De Doctrina?

Comparison of De Filio with Book 1, Chapters 10 and 4

De Filio resembles Milton's other very distinctive and personally prized chapter, where he argues that scripture allows (if it does not also advocate!) divorce. The resemblance does not reside in subject matter (since I.10 concerns conduct not belief), or in structuring (since I.10 grew like Topsy). It resides in the peculiar way of reasoning on which I focus, peculiar in the sense of “strange” but equally “all his own,” his peculium. In both chapters alike Milton knows in advance what he will find in scripture—or in the case of De Filio, not find. In both he makes himself the arbiter of letter and spirit in texts which he has arbitrarily—by his own judgment—allowed or disallowed. Indeed, the two chapters resemble each other closely even by their contrast. For in the one case he pushes to extend meaning, to open up the received meaning; in the other he limits and disallows such extension by others. Thus either way, orthodoxy is misguided and stands in need of his correction.

These fluctuations within intensity and commitment make De Doctrina more, not less compelling. In I.10 he startles and awakens those who thought the meaning of gospel teaching was straightforward. In I.4 he delivers a structured argument of great force and wide range about predestination: here he is no piecemeal Ramist, but an almost orthodox Arminian. In De Filio, he restricts and reduces, at an opposite extreme (as said) to I.10, while attempting an argument both longer and more ambitious, yet less open, than in either of the other chapters. And the register rises to moments of righteous anger