Philosophy of psychiatry explores philosophical questions relating to psychiatry and mental illness. In Japan, such questions have mainly been discussed in the field of psychopathology. The Japanese tradition of psychopathology has been influenced by so-called continental philosophy, such as hermeneutics, phenomenology, and psychoanalytic theory. On the other hand, philosophy of psychiatry is closely related to philosophy of science and philosophy of mind. In spite of this theoretical difference, I suppose that philosophy of psychiatry will provide interesting points of view for Japanese psychiatrists.
 To show how philosophy of psychiatry will contribute to Japanese psychiatry, in this paper, I compared two theories on understanding the mental state of others. One of them is Jaspers'account of understanding (Verstehen). Japanese psychiatrists have regarded understanding through empathy to be a fundamental approach of psychiatry. The other is simulation theory. Simulation theory is one of the main accounts of mind-reading in philosophy of mind.
 Jaspers presented understanding, especially empathic understanding (einfühlende Verstehen), as a method to comprehend others' mental states from within. Jaspers' notion of empathic understanding seems partly to come from Lipps' theory of empathy (Einfühlung). Lipps argued that perception of others' expressions arouses a tendency to reproduce them and this tendency evokes the feeling which is normally associated with the expression. This feeling is then attributed to the other, thereby allowing for interpersonal understanding. This process is based on empathy, which involves a drive directed towards imitation and a drive directed towards expression. Therefore, it can be said that understanding others through empathy involves imitating and reproducing others' states in oneself.
 The same idea can be found in simulation theory. In recent years, simulation theorists (cognitive scientists) have argued that the mental states of another person can be explained and predicted by performing a simulation using one's own mind (or brain) as a model. That is, one replicates or reproduces in their own mind (or brain) the same state as the target's mental (or neural) state (with the function of the mirror neuron system, for example), then attributes the thoughts and emotions felt in that state to the target.
 Lipps' empathy theory and simulation theory seem to be the same in their assumption that imitating others is the basis of understanding others. However, there are differences between Jaspers' notion of empathic understanding and simulation theory of understanding others' minds. One difference is in the level of the topic and the other is in the subject matter. First, Jaspers considered understanding to be the personal level practice of the psychiatrist. On the contrary, simulation theorists focus on sub-personal level mechanisms underlying the understanding of the mind. Second, Jaspers supposed understanding (and empathy) to be a means to know the mind. His subject matter is the scope and limit of that means. On the other hand, the subject of simulation theory is understanding (or empathy) itself.
 These differences indicate that clarification of the scope of empathic understanding in psychiatry requires a viewpoint other than simulation theory, although the mechanism of empathy may be elucidated in the framework of the simulation. In addition to this point, it should to be noted that a clear awareness of the level and the domain of the subject matter is significant for a discussion of understanding of the mind. This comparative inquiry of empathic understanding and simulation theory produced the above points. This result seems to indicate that philosophy of psychiatry useful for Japanese psychiatrists for examining conceptual issues in psychiatry.
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