The sources of knowledge in psychogeriatrics.

Whether called psychogeriatrics, old-age psychiatry, geriatric psychiatry, geriatric psychology, or mental health of the elderly, the clinical disciplines focusing on the mental health problems of older individuals are increasingly becoming recognized as subspecialties of their parent disciplines. Although the rate at which this is occurring is variable, interest is spreading worldwide and will continue to grow. Perhaps the single greatest important justification for the growth of psychogeriatrics as a subspecialty is the accumulation of a unique database relevant to the mental health problems of older individuals. This is evidenced by the large number of textbooks on geriatric mental health, the increasing membership of the International Psychogeriatric Association and other national societies, and the increasing number of journals whose primary focus is on late-life mental health and illness. Where does this knowledge come from? This is a crucial question because developing a consensus on what knowledge is important to a field is a necessary step in the growth of that field. One century ago, the sociologist Max Weber distinguished between two types of knowledge. This distinction actually goes back to Aristotle. The philosopher and psychiatrist Karl Jaspers adapted this distinction to psychiatry, labeling the two types of knowledge ”explanation” (“Erklarung”) and ”understanding” (“Verstehen”). The first type of knowledge, and the one most recognizable, is what might be called empirical or ”scientific” knowledge. It is knowledge that can be confirmed by performing research that meets criteria for validity and rigor. Because the methods of science evolve, the types of studies done and the methods used have changed over time. Although there is a debate about whether a single ”scientific method” exists, explanatory knowledge depends on the ability to test and refute hypotheses prospectively. Undoubtedly, hypotheses about late-life mental disorder will continue to be tested. The results gained from these studies will remain important sources of knowledge for increasing the database of psychogeriatrics. The second form of knowledge, understanding, is gained through the empathic method and depends on the methods of empathy, meaning, and narrative. The ultimate validation of this method is an agreement among the people holding the idea that this knowledge is valid. For example, if a clinician and a patient agree that failing health is a