There are currently very few discussions of moral psychology in the animal ethics literature. This dissertation aims to fill this void. My main contention is that many theories in animal ethics hold mistaken views about the moral psychology of human beings. These mistaken moral psychological views, I argue, limit these theories' ability to act as a guide in people's treatment of animals. To develop my argument, I propose five criteria by which to assess the psychological plausibility of ethical theories, drawing from numerous recent developments in empirical moral psychology. I also draw a comparison between cases of physical impossibility in the "ought implies can" literature and cases of psychological difficulty, primarily as they arise in the literature on moral ideals. In both cases, I argue, limitations in individual resources constrain what ethical theories can ask of individuals. I then investigate three different topics relevant to human moral psychology and normative evaluation of animals: attributing mental states to animals, the status of animals as disgust elicitors, and our empathic responses to animals. With respect to mental state attribution, I argue that the best research to date indicates that phenomenal mental states, like pain, determine our judgments of the moral considerability of animals. I also argue that the behavioral triggers we possess for attributing phenomenal states to animals are quite narrow--primarily animals that look and act like human beings. With respect to disgust, I examine research suggesting animals elicit disgust-based avoidance. I draw from research on dehumanization to argue that one way we cope with animals, despite their disgust-evoking powers, is by attributing them mental states that evaluate them positively but simultaneously cement their status as inferior beings. In the case of empathy, I argue against the idea that empathy is psychologically central to expressing moral concern for animals. I examine six empirical claims made about empathy in the animal ethics literature and argue that all six are problematic to varying degrees. I conclude by making suggestions for overcoming specific psychological obstacles identified throughout the dissertation. I also outline a research plan for constructing psychologically plausible theories in animal ethics.
