ABSTRACT
A major aim of the social and behavioural sciences is to develop principles which explain and provide new insights into human behaviour. One way of evaluating what appear to be sound and promising principles is to examine the extent to which they are consistent with carefully controlled observations of human behaviour. In other words, the validity of principles needs to be tested by conducting empirical research wherever possible. If the data do not agree with the principle under scrutiny, the principle may have to be modified and then re-examined. Alternatively, the way in which the controlled observations were made may have been mistaken and a new set of data may have to be collected. Suppose, for example, we tested the idea that people are likely to repeat the aggression they see in others but we found no evidence to support such a relationship. In this case, it might be necessary to make the principle more specific by proposing that individuals are likely to imitate aggression which is rewarded rather than punished, and then to test this revised proposition. On the other hand, the measure of aggression we used may have been unsuitable for the purpose and may have to be replaced with a more appropriate test.
