George Engel's biopsychosocial model is widely accepted in psychiatry because it enables different theories and methods to coexist. In his recent books, Nassir Ghaemi criticized this model as a version of eclecticism. He claimed that the model tells us to always keep three factors in mind and does not provide a specific scheme for treatment. As an alternative to eclecticism, Ghaemi proposed pluralism, which tells us to apply different methods to different diseases on a certain methodological basis. If we can understand the relationship between the mind and the brain in an analogous way as we understand the relationship between the software and hardware of a computer, pluralism may be a plausible view of psychiatry. Ghaemi claimed, however, that there are two fundamentally different methodologies, causal explanation and meaningful understanding, in psychiatry. If we also accept this claim, it will be difficult to maintain the analogy between mind/brain and software/hardware. How to accommodate the plurality and unity of psychiatry remains one of the most important theoretical issues.
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