DOXA is ‘common belief’. Another familiar translation of this Ancient Greek term (from the verb <dokein>, meaning ‘to appear’, ‘to seem’) is popular opinion. In classical rhetoric, <doxa> is opposed to <episteme> (scientific knowledge). Then in turn <episteme> and <doxa> are different from <techne> (craft or applied practice).

Platon (Plato) describes the Sophists as wordsmiths who unscrupulously use the <doxa> of the multitude to their own advantage. In this sense <doxa> is a belief with no relation to reason [see also <dogma>], a major concern in Western philosophy.

<Doxa> is ‘common belief’. However, in Platon’s books Theaetetus and Meno, we find the notion that knowledge is <orthos doxa>. And the distinctive trait of  this particular <doxa> is that one can provide a <logos> for it. So it leads to the traditional definition of knowledge as justified true belief.

Again it is Platon to sustain that <doxa> resides in the unreasoning, lower-parts of the soul. This standpoint evolves into the notion of doxasta in Platon’s theory of forms. This theory says that physical things are manifestations of <doxa> and so they are not in their true form.

Platon’s definition of <doxa> as the opponent of knowledge leads to the traditional opposition of error and truth. Thus, error is negative and can take various forms, among them the form of illusion. In short, it is clear that reasonable viewpoints need the support of solid reasonings. Otherwise they are errors and illusions. Nonetheless we know from our own experience that the circulation of <doxa> is widespread, particularly in our web societies. Also we know that frequently it is not easy to differentiate between <doxa> and <episteme>.