Hur kan vi veta vad djuren tror?
How can we know what animals believe?
In this article I will contrast two ways of viewing a possible connection between animal and human rationality: that of Alasdair MacIntyres Aristotelian naturalism, where the continuity between the animal and the human is based on our biological nature; and Wittgensteins notion of primitive reactions as it appears in Norman Malcolm and others. The notion of primitive reactions differs from MacIntyres in that instead of revealing continuity in intellectual capacities between animals and humans, it points to a similarity in our responses to human and animal behaviour. I argue that this is not (either for Wittgenstein or for Malcolm) to make an empirical point about the development of language from instinctive behaviour, but is rather a conceptual point: an elucidation of what we mean by the mental terms we use, i.e., what we mean by ascribing thoughts, beliefs or feelings to someone.