Against the Physicists (Adversus Mathematicos IX–X)

Sextus organizes the two books into nine successive topics: god, cause, wholes and parts, body, place, motion, time, number, and coming-to-be and passing-away . These are the fundamental principles of ancient Greek natural philosophy, and Sextus treats them together because they form an interconnected system. If any one of these principles collapses under skeptical scrutiny, the entire edifice of dogmatic physics is compromised. The arrangement is not arbitrary: each topic builds on the previous ones, and Sextus shows how the difficulties encountered in one area ramify into the others. The result is not a piecemeal critique but a comprehensive dismantling of the pretensions of physical science to certain knowledge.

Bury's Loeb edition (1936) was the standard English translation for over seventy-five years . Bett's Cambridge edition (2012) is the first new English translation since Bury, and it differs in significant ways. Bett prioritizes fidelity over elegance, translating technical terms literally to preserve their connections to ordinary Greek usage—for example, rendering ἕξις as 'holding' and φαντασία as 'appearance' . His edition includes an outline of the entire argument, extensive footnotes discussing philological and philosophical issues, a glossary, and a list of parallel passages in Sextus's other works . For scholarly work, Bett's edition is now the standard; Bury's remains useful for its facing-page Greek text and its historical importance.

The two works overlap substantially. Book III of the Outlines covers much of the same ground as Against the Physicists, but in a more compressed form. The Stanford Encyclopedia notes that when Sextus refers to his own works, he sometimes points to passages that exist in both the Outlines and Against the Physicists, indicating that the latter is the fuller, more extensive treatment . Against the Physicists is not a replacement for the Outlines but a more detailed working-out of the same skeptical strategies. Readers seeking the systematic overview should start with the Outlines; those seeking Sextus's most thorough engagement with the arguments of the dogmatic physicists should turn to the two books against the physicists.

The section on cause is one of the longest in the work because causation is the hinge on which dogmatic physics turns. If causes can be identified with certainty, then the project of explaining nature rationally is possible; if not, the entire enterprise falters. Sextus deploys a range of arguments: that cause and effect must be simultaneous or successive, and neither is coherent; that the relation between cause and effect cannot be known; that different schools disagree irreconcilably about what causes what. The point is not to establish a skeptical theory of causation but to generate suspension. As the editors of a recent volume on the work note, Sextus's aim is to restore tranquility to those troubled by their inability to resolve the anomalies raised by the study of nature—the arguments are therapeutic in intent, even when they appear sophistical .

The section on god (M 9.13–194) is the longest single treatment in the work. Sextus does not attack religious practice or piety; he attacks the pretensions of philosophical theology to demonstrate the existence and nature of god through reason. He assembles arguments for and against the existence of god, showing that the dogmatists' proofs are equipollent with the counter-arguments. The target is not faith but the claim that reason can establish theological truths with certainty. This distinction is important: Sextus's skepticism is not atheism, which would be a dogmatic position, but suspension of judgment about what god is or whether god exists. The skeptic lives by appearances and customs, which may include religious practices, without dogmatizing about their metaphysical foundations.

The text depends on three primary manuscripts: L (Laurentianus 85.11), E (Parisinus gr. 1964), and N . The manuscript tradition is complex, with later copies and a significant number of corrections and emendations introduced by editors. Bury's edition was based on Bekker's text with deviations noted in footnotes . Bett's edition largely follows Mutschmann's canonical Teubner edition (1914), occasionally incorporating emendations from Heintz (1932) and Blomqvist (1968), but Bett is generally more conservative than his predecessors, preferring to follow the manuscripts unless they yield impossible results . Readers should be aware that some passages are corrupt or confused, and the translation necessarily involves editorial judgment about how to handle them.