This dissertation is an investigation into the relation between mind and language from different perspectives, split up into three interrelated but still, for the most part, self-standing parts. Parts I and II are concerned with the question how thought is affected by language while Part III investigates the scope covered by mind and language respectively. Part I provides a reconstruction of Ludwig Wittgenstein’s famous Private Language Argument in order to apply the rationale behind this line of argument to the relation (...) between mind and language. This argumentative strategy yields the conclusion that reasoning – an important type of thought – is constitutively dependent on language possession and is therefore not available to non-linguistic creatures. This result is achieved by considering the preconditions for reasoning – given that it is a rule-governed activity – and eliminating competitors to language for providing reasoners with what it takes to reason. Part II provides a critical outlook on the wide and highly heterogeneous field of linguistic relativity theories. It is argued that no kind of linguistic relativity whatsoever follows from the conclusion of Part I – i.e., the claim that reasoning is constitutively dependent on having a language. While Part II does not provide a conclusive argument against the linguistic relativity hypothesis, it is argued that endorsement of linguistic relativity theories often rests on a mistaken assumption to the effect that language and culture are interwoven in a way which makes it impossible to separate culture and language, as well as their respective studies. This assumption is undermined by providing examples of languages which clearly predate their culture or do not even have a culture at all. So, the assumption that language and culture are inextricably intertwined is refuted by way of counterexample. Part III provides an in-depth examination of the Principle of Expressibility – prominently endorsed and formulated by John Searle – which claims that whatever can be thought can also be said. The domains of what can be thought and of what can be said are considered in set theoretic terms in order to determine whether one is contained in the other, so that everything we can think can also be adequately communicated. After thorough study of interpretative issues regarding the Principle of Expressibility and consideration of the most pressing potential counterexamples to the principle, we can conclude that we have good reason to believe in the truth of the Principle of Expressibility. In conclusion, the achieved results are related back to prominent positions in the discussion about thought and language which already make their appearance in the very beginning of this investigation. The final chapter of this dissertation reminds us that eminent figures in philosophy have often taken a wrongheaded perspective on the relation between language and thought, so that language has frequently appeared to be an impediment to thought. We can, however, confidently conclude that language, on the contrary, is by far our most apt means for thought and that reasoning would not even be possible without the resources language provides. (shrink)