INTRODUCTION

We quite naturally attribute mental representations in order to explain actions. The cat is scratching at the door because he wants to come in the house and believes that scratching at the door will get him into the house. The dog is following me because she wants some of my food and believes that by following me she can get some of my food. Some of our attributions of mental representations are without doubt fanciful (does my car really not like to start on cold mornings?), but some of these attributions are accurate. For example, some, if perhaps not all, of the actions of adult human beings are properly explained by their desires and their beliefs about how to achieve those desires. What about the behavior of (non-human) animals? Are belief-desire explanations the right explanations of their actions? I argue that some (non-human) animal behavior is properly so explained, and thus that some animals truly have beliefs and desires. There are two strands of evidence which separately support this conclusion. First, behavior that is appropriately explained in terms of mental states such as beliefs and desires is behavior directed at a goal relative to which the agent is able to learn; and since human behavior meets this criterion, I argue, we should expect, on evolutionary grounds, that some animal behavior meets this criterion as well.