EN
This article focuses on the presentation of the basic forms of scepticism and sceptical argumentation denying the possibility of gaining knowledge in the sense of its tripartite definition (justified true belief). The author presents a selection of historical objections to the attainability and knowability of truth and the possibility of gaining complete or adequate true justification of knowledge, but also objections concentrating on the understanding of knowledge as conscious and fully-reflected true belief. In the second part of the article the author attempts to argue against advocates of the unjustifiability of knowledge (holding that there do not exist any sufficient or partly good reasons for knowledge) by pointing to the existence of various levels of persuasiveness of particular opinions and beliefs and by showing the meaninglessness of the distinction between knowledge and supposition in conceptions that deny knowledge any kind of good reasons. In conclusion there is an attempt to demonstrate that falsification of a certain piece of knowledge is itself a piece of knowledge that is grounded on the adequate reasons of its soundness.