The purpose of this thesis is to search for ways in which Freud’s and Lacan’s psychoanalytical theory can contribute to Austin’s and Wittgenstein’s philosophies of language. We propose that the subject of Austin’s speech acts be framed within Freud’s theory of parapraxis as acts of the unconscious, so that the Freudian concept of drive can be related to speech as an act of a subject. The speech act is, then, thought as being subordinate to the vicissitudes of what Lacan called the Great Other, since the act occurs in what Lacan named the symbolic order. As to Wittgenstein’s theory, the focus of this work is on its relations to Lacan’s claim that the unconscious is structured like a language. The psychoanalytical concept of the unconscious is here used to consider the relations between language and subjectivity and the way how the subject accesses the world through language; in other words, the focus is on the relations between the subject of the unconscious and the subject of language.