Against the Ethicists (Adversus Mathematicos XI)

The work is divided into two parts. The first part (M XI.1–41) argues that no art or science of life exists: the dogmatists' claims to know the good, the bad, and the indifferent by nature cannot be sustained. The second part (M XI.42–167) attacks the ethical 'art' (technē) directly, arguing that even if one had such knowledge, it would be useless for living. The two parts are complementary: the first shows that the theoretical foundation is unavailable, the second shows that even if it were available, it would not deliver the practical benefits the dogmatists promise. The structure reflects Sextus's broader strategy: to present arguments against the possibility of a science of ethics, and then to show that the science, even if possible, would not improve human life.

The distinction is fundamental to ancient ethical theory. Dogmatists—Stoics, Epicureans, Peripatetics—all claimed that some things are good by nature (virtue, wisdom), some bad (vice, suffering), and some indifferent (health, wealth, reputation), and that the wise person can distinguish them with certainty. Sextus attacks this by deploying equipollent arguments: for every reason to think that something is good by nature, there is an equally strong reason to think it is not. The disagreement among the dogmatists themselves is evidence that no rational settlement has been reached. If the distinction cannot be secured, the entire edifice of dogmatic ethics—the claim to know how to live—lacks its foundation. Suspension follows, and with it the skeptic's unperturbedness.

Bury's Loeb edition (1936) was the standard for over sixty years, with facing Greek text, but it was based on a text that had not been thoroughly re-examined. Bett's Clarendon edition (1997) is the first full English translation of Against the Ethicists since Bury, and it includes a substantial introduction that argues for a specific interpretation of the work: that the two parts are addressed to two different positions, with the first part targeting those who think ethics can be a science but cannot be a technē, and the second targeting those who claim there is an ethical technē whose rules yield happiness. Bett's translation is more literal and philosophically precise; his notes engage with the Greek text and the philosophical issues. For scholarly work, Bett's edition is now standard; Bury's remains useful for its Greek and its historical importance.

Sextus's arguments in the second part are aimed at the claim that ethics is a technē—a systematic art that can teach people how to live well. He argues that the rules and precepts of ethical systems are either too general to be useful or too specific to be teachable. Ethical knowledge would not be like medical knowledge, which produces predictable effects in the body; the effects of ethical teaching depend on the character, circumstances, and opinions of the learner, and no art can control these. He also argues that ethical knowledge would not be sufficient for happiness, since happiness depends on external goods and circumstances beyond the agent's control. The conclusion is not that ethical knowledge is impossible but that its practical value is illusory—a conclusion with the same therapeutic effect: it liberates the skeptic from the anxiety of needing to know.

Outlines Book III is the condensed version of the same material, covering ethics in a more summary form. Against the Ethicists is the fuller treatment, with more detailed arguments and more extensive engagement with the dogmatic schools. Readers new to Sextus should begin with the Outlines, which provides the framework for understanding the later works. Those who want the full argument against the possibility of a science of ethics should turn to Against the Ethicists. Bett's introduction to his translation notes that the two works differ not only in length but in focus: the Outlines is concerned with the general skeptic's way of life, while Against the Ethicists is a specific polemic against the claim of ethics to be a technē. The relationship is one of compression and expansion, not of contradiction.

The skeptic does not live without ethical guidance; he follows appearances, customs, and the laws of his community, without dogmatizing about their metaphysical foundation. Sextus describes this as 'following the appearances'—the skeptic lives in a way that is guided by the natural inclinations of the body and the traditions of his society, but he does not assert that these are true or good by nature. The critique of ethics does not leave the skeptic without a way of living; it leaves him without a theory of why he lives that way. This is the therapeutic point: the anxiety about knowing the good is removed, and the skeptic finds that tranquility follows, not because he has solved the moral problem but because he has suspended judgment about it. The life of the skeptic is thus a practical alternative to both dogmatic ethics and nihilistic despair.