Psychology as a Science

Psychology, like other sciences, seeks to describe, explain, predict and control the events it studies. Psychology thus seeks to describe, explain, predict, and control behaviour and mental processes.
Psychological theories are based on assumptions about behaviour and mental processes, contain statements about the principles and laws that may govern them and allow us to derive explanations and predictions. Many psychological theories combine statements about behaviour (such as eating or aggression), mental processes (such as attitudes and mental images), and anatomical structures or biological processes. For instance, many of our responses to drugs such as alcohol and marijuana can be measured as overt behaviour, and they are presumed to reflect the biochemical actions of these drugs and our (mental) expectations about their effects.
A satisfactory psychological theory allows us to predict behaviour and mental processes. For instance, a satisfactory theory of hunger will allow us to predict when people will or will not eat. A broadly satisfying comprehensive theory should have a wide range of applicability. A broad theory of hunger might apply to human beings and lower animals, to normal-weight and over-weight people, and to people who have been deprived of food for differing lengths of time. If our observations cannot be adequately explained by, or predicted from a given theory, we should consider revising or replacing that theory.
In psychology, many theories have been found to be incapable of explaining or predicting new observations. As a result, they have been discarded or revised. For example, the theory that hunger results from stomach contractions may be partially correct for normal-weight individuals, but it is inadequate as an explanation for feelings of hunger among the overweight. Contemporary theories focus also on biological variables and situational variables.
The notion of controlling behaviour and mental processes is controversial. Some people erroneously think that psychologists seek ways to make people do their bidding--like puppets on strings. This is not so. Psychologists are committed to a belief in the dignity of human beings, and human dignity demands that people be free to make their own decisions and choose their own behaviour. Psychologists are learning more all the time about the various influences on human behaviour, but they implement this knowledge only upon request and in order to help an individual or organization.