Suspending judgment › The Five Modes: Examining Justification

The five modes attributed by Sextus to later skeptics concentrate the challenge to justification (I.164–169). Their distinctions are easier to follow when kept separate:

1. Disagreement: competing positions remain unresolved, leaving the inquirer without a basis for choosing between them.
2. Regress: the support offered for a claim requires further support, and that further support requires more, without an available starting point.
3. Relativity: an object appears in relation to the judging subject or to other things, while what it is independently remains disputed.
4. Hypothesis: an unsupported starting assumption is introduced to stop the demand for reasons.
5. Reciprocity: what is offered as support itself depends on the claim it was supposed to establish.

The familiar contrast between regress, unsupported assumption, and circularity should not obscure the other two modes. Sextus here attributes the five modes to later skeptics without naming Agrippa in his own text. Understanding how the modes work does not require settling the further history of their development.

Here is a modern illustration of reciprocity. A team treats a rating system as reliable because it agrees with an expert. Asked why the expert is reliable, it answers that the expert agrees with the rating system. Neither answer adds support independent of the disputed pair. This makes the circularity visible. It does not establish that every practical use of ratings has that defect, or that every form of mutually supporting evidence fails in the same way.

Sextus applies a related challenge to a criterion of truth, meaning a standard for judging which claims are true. At II.18–20, he asks how disagreement about such a criterion will be settled. An agreed criterion seems needed to decide the dispute, while deciding the dispute seems needed to secure an agreed criterion. Trying to prove the criterion introduces another reciprocal dependence if the proof itself needs that criterion. The point is a challenge to the proposed justification, not a discovered theorem that no standard can ever exist.