"Certainty" occupies an important place in Wittgenstein’s epistemology: it does not belong to the category of knowledge but constitutes its foundation. In his view, knowledge boils down to language games, and language games are based on indubitable certainties. According to Wittgenstein, scepticism is meaningless, and if there is no certainty, then even doubt would be meaningless. Wittgesntein maintains that [relative] doubt and knowledge are epistemic categories, whereas absolute doubt and certainty are non-epistemic categories. Epistemic categories are meaningful and when expressed (...) by means of statements could be either true or false. In contrast, non-epistemic categories are meaningless and when expressed by means of statements the properties of truth and falsehood do not apply to them. The aim of the present paper is two fold: 1- Providing an explanation of the status of certainty in comparison to categories such as doubt and knowledge in Wittgenstein’s thought; 2- Providing a critical assessment of Wittgenstein's approach to certainty through the prism of critical rationalism. The main arguments of the paper are as follows: 1. Although Wittgenstein considers certainty to be meaningless and therefore not on a par with epistemological categories, he regards it as an objective concept that functions as the foundation upon which all human knowledge is based; 2. Wittgenstein's efforts to show the objectivity of certainty have not been entirely successful, partly due to his reliance on a defective notion of ‘objectivity’ and partly as a result of the prominence he assigns to the category of ‘meaning’ at the expense of the category of ‘truth’. (shrink)