 The different positions on mental disorder just sketched—emphasizing internal conditions, observable manifestations, and both—are discussed in  Section 4.  Each position exhibits vulnerabilities. Accounts stressing inherent features regularly rely on hypothetical entities or processes, expecting that out of future discoveries will emerge knowledge of causal mechanisms presently hidden from view. (This position has a long history; for a recent version, see Murphy 2007.) Perhaps explained by its status as a new science, this faith has been sorely tested, thus far, by confused classifications, apparently ill grounded research, and other liabilities, as well as incomplete models of mental dysfunction (see  §4  and  §6).  If these impediments can be overcome, emphasis on internal causes may be expected to yield powerful explanatory models, laying the ground for the incalculably valuable targeted interventions and effective prevention and treatment sought by all. (See entry on Philosophy of Psychiatry). Placing emphasis on disabling or dysfunctional symptoms has comparable vulnerabilities associated with relativism. One setting’s dysfunctional mental symptom may be another’s normal, admired, or useful trait; and mental disorder must be distinguished conceptually from deviance, as well as from normal responses to the losses and setbacks that are our common human experience (these issues are discussed in  §4,  §8, and  §10).