These two theories have created debates between psychologists for many years., is one of the world's most cited psychologists. He is a professor at the Institute of Psychiatry of the University of London, where he started the discipline of clinical psychology in Great Britain. He is a pioneer in the use of behavior therapy as well as research in personality theory and measurements. .
The biological theory has to do with his findings that individual differences in personality are biology based. This was based on his theory that there are three dimensions of personality (super factors). These dimensions of personality were extraversion-introversion, neuroticism, and psychoticism. To check his work by using cross-cultural studies that produced much the same conclusion. Hans also went a step farther in pointing out the results of many studies indicating that genetics play an important role in deciding the amounts of which of the three personality dimensions one might possess. There are many pro's and con's to this theory but most psychologist will admit that it is getting increasingly harder to ignore the obvious link between our evolutionary history and our genetic makeup. There are some weaknesses to this theory. There is criticism that several of the ideas can't be tested in actual experiments. The psychologists are prone to use reasonable deduction in many instances, which may not give an accurate assessment. For example several types on direct manipulation would be illegal to perform which makes demonstrations of cause and effects difficult. There are other concerns over the research on temperament. There doesn't seem to be an agreement on the number of dimensions. In the EAS temperament model there are three dimensions identified, but there are several other models in use that describe additional dimensions. This creates a problem for psychologists and students alike in confirming which is the correct model.