This paper examines the discussion about false pleasures in the Philebus (36 c3-44 a11). After stressing the crucial importance of this discussion in the economy of the dialogue, it attempts to identify the problematic locus of the possibility of true or false pleasures. Socrates points to it by means of an analogy between pleasure and doxa. Against traditional interpretations, which reduce the distinction drawn in this passage to a distinction between doxa and pleasure on the one hand and their object on the other, it is argued that, rather, Socrates distinguishes between the mere fact of having a doxa or a pleasure, on the one hand, and the content of these acts, on the other hand. Consequently, the possibility for a pleasure to be false does not concern its relation to an object, but the affective content which defines it. In order to show how the affective content of a pleasure can be false, it is necessary to examine the three species of false pleasures described by Socrates in their relation to appearance and imagination. Appearance is not identical with perception for Plato: it consists in a mixture of perception and doxa. As for imagination, it consists in "illustrating" a doxa present in the soul by means of a "quasi-perception". It is the presence of a doxa in each of these processes which makes it possible for them to be true or false, while mere perception cannot be either true or false. It is then argued that according to the Philebus pleasure can be false precisely because its affective content is not a mere perception, but either an appearance or an imagination.