The paper deals with the art of cross-examination or probe (peirastiké) wich is, according to Aristotle, a part of dialectic and aims at revealing falle pretensions to knowledge. A detailed discussion of the relevant passages from the Sophistical Refutations shows that "peirastic" argumenta were not easily distinguishablc forro the arguments used by the sophists against the scientists in order to undermine their reputation. It is also shows that the difficulty of telling dialectic from sophistry is a theme Aristotle inherits frorn (...) Plato's Sophist. (shrink)