Abstract
Knowledge of an individual is permanently dynamicaly shaped not only by his contact with ´non-sentient´ nature, but mostly by his interaction with other cogniting subjects. This interaction is mediated through language and often takes form of dialogue, whose one particular form is argumentation (other forms of dialogue are for example explanation, negotiation etc.).
In argumentation cogniting subject (agent) confronts his knowledge and it´s justification with knowledge and justifications of other agent. Mathematical models of argumentation then specify rules by which argumentation is processed and resolved.
We are interested only in argumentation based on logical arguments, those whose claim is logically entailed in their ´s premises.