Objectives:
To characterize rationale and argumentation as subjects of scientific research. To represent application of rationale and argumentation technology in on-line discussions on the basis of selected examples.

Material and methods:
Analysis and generalization of scientific sources and documents was performed. Practice of using rationale and argumentation in on-line discussions was analyzed. The first discussion is an on-line dialog between a philosopher and an economist. The philosopher refutes the stereotypical position of his opponent consisting in denying importance of the humanities for the society and in the desire to achieve the abolition of funding for all humanitarian researches. The second example concerns the selection of arguments for dispelling the mythological worldview formed by the means of the Russian information propaganda regarding the Russian-Ukrainian war.

Results:
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Conclusions:
In the age of information society, when information aggression is growing and increasingly turning into an information war, it is essential to be able to rationalize and argue own position as well as to unmask false statements. This skill is especially important in counteracting mythologization of the society and spread of stereotypes.