On relationship between logic and rhetoric and on logical rules vs. rhetorical moves of debate. The opposition \u2018logic/rhetoric\u2019 represents a fundamental cultural antagonism. Surprising as it may seem, contemporary revival of the art of rhetoric has not been promoted primarily by scholars or professional users of rhetoric, but developed itself through alternative, unusual paths, such as those of epistemology, logic and science. This is the case of the theory of knowledge (Polanyi) or of the improvements brought to informal logic by Perelman and Toulmin. As far as our specific interest in rhetoric is concerned, significant contributions to the history of science as well as to the Philosophy of Science have been made (by Thomas Kuhn ...