If we already had a periodic table of mental illness in hand, there would be less need for a book of this type. Although some psychiatrists do think of themselves as chemists, the analogy is without warrant. Not only does psychiatry lack an analogue of the periodic table, its principal tool -- the Diagnostic and Statistical Manual of Mental Disorders (DSM) -- is a contentious document. Even subsequent to the publication of DSM-III in 1980, which was intended to serve as an operational guideline for clinical practice, it and its heirs (DSM-V was published in 2013) have often fueled rather than quelled controversy. Although beginning with that third major revision of DSM a concerted effort has been made to ensure greater consistency in diagnoses, psychiatry remains beset by concerns that it is insufficiently scientific, unduly influenced by the pharmaceutical industry, indecisive as to whether it should focus on the mind or the brain, incapable of distinguishing among types of diseases, inclined to expand illness criteria without adequate justification, overly reliant on subjective judgments, wont to conflate clinical and ethical judgments, and engaged in indiscriminate use of psychoactive drugs. These worries concerning its scientific and ethical status are among the reasons that psychiatry attracts the attention of philosophers.