Psychology as a Natural Science

Modern psychology grew out of philosophy, but what turned it into a science was its adoption of the scientific method, which places a premium on objectivity -- achievable only when there is agreement on how a concept is defined and measured. Influenced by Descartes and later by developments in physics, this branch of psychology follows what is called the hypothetico-deductive model: scientific progress happens when a theory (an interrelated set of statements explaining a complex phenomenon, the way the Big Bang theory explains the origin of the universe) is used to deduce a hypothesis, a tentative, testable prediction, which is then checked against empirical data. If the data do not support the hypothesis, the theory itself is revised. Working this way, psychologists have built up substantial, well-tested theories of learning, memory, attention, perception, motivation, and emotion, and this remains the dominant approach in psychological research today. A second major influence on this natural-science stream is the evolutionary approach borrowed from biology, which has been used to explain psychological phenomena such as attachment and aggression as outcomes of evolutionary pressures rather than purely of an individual's personal history. …