A concern with contemporary psychology and psychiatry is that they assume too much on the basis of clinical assessments prone to many sources of error. These sources of error may include unreliable or invalid test administration and/or interpretation or even variable patient responses over time. It would be difficult to prove that mental health science is based on undeniable fact. Mental health professionals may have enormous privilege bestowed upon them that may be inadvertently used to judge others and even influence life changes upon their patients - sometimes to their patients’ detriment. Mental health science, with the tenet, ‘do no harm’, is arguably one of the toughest sciences of all.