 According to Aristotle, human beings can reason in ways that non-human animals cannot. They can deliberate about what to do, about what kind of lives to live, about what sort of persons to be. They can look for reasons to act or live one way rather than another. In other words, they can engage in practical reasoning. They can also think about the nature of the world and why it seems to behave as it does. They can consider scientific and metaphysical truths about the universe. This is to engage in theoretical reasoning (“contemplation” or theôria). There is no agreement among scholars as to whether, and how, these types of reasoning can be distinguished. (For a discussion of theoretical and practical reason in Aristotle, see the related entry on  Aristotle’s ethics.)  But as we shall see when we discuss Aristotle’s Politics, we can assume, for the purposes of this discussion, that theoretical and practical rational activity are at least related types of rational activity, in that each involves exercising one’s abilities to think and to know and to consider truths that one has figured out.