Nomothetic Approach To Personality Definition Essay

Nomothetic Idiographic Debate

Saul McLeod published 2007

This is one of the main philosophical debates in psychology.

The term “nomothetic” comes from the Greek word “nomos” meaning “law”.  Psychologists who adopt this approach are mainly concerned with studying what we share with others. That is to say in establishing laws or generalizations.

The term “idiographic” comes from the Greek word “idios” meaning “own” or “private”. Psychologists interested in this aspect of experience want to discover what makes each of us unique.

Despite the fact that an important aspect of our uniqueness is our genes (i.e. it comes from biology) the distinction between the nomothetic and the idiographic is often equated with two types of science – the natural sciences concerned with discovering laws of nature and the social sciences with individual meanings. We can examine these differences further by seeing how they relate to personality theory.


The psychometric approach to the study of personality compares individuals in terms of traits or dimensions common to everyone.  This is a nomothetic approach and two examples are Hans Eysenck’s type and Raymond Cattell’s 16PF trait theories. The details of their work need not concern us here.  Suffice to say they both assume that there are a small number of traits that account for the basic structure of all personalities and that individual differences can be measured along these dimensions.

In the past 20 years a growing consensus has begun to emerge about what those traits are.  The “big 5” are considered to be extroversion, agreeableness, conscientiousness, emotional stability and openness to experience. From a nomothetic point of view these are considered to adequately describe the psychologically significant aspects of any personality.

At the other extreme Gordon Allport found over 18,000 separate terms describing personal characteristics. Whilst some of these are common traits (that could be investigated nomothetically) the majority, in Allport’s view, referred to more or less unique dispositions based on life experiences peculiar to ourselves. He argues that they cannot be effectively studied using standardised tests.  What is needed is a way of investigating them idiographically.

Two psychologists who have developed methods of doing this are George Kelly with his repertory grid technique and Carl Rogers who has made extensive use of a procedure called the “Q-sort”. What this entails is as follows.  First the subject is given a large set of cards with a self-evaluative statement written on each one.  For example “I am friendly” or “I am ambitious” etc. The subject is then asked to sort the cards into piles.  One pile to contain statements that are “most like me”, one statements that are “least like me” and one or more piles for statements that are in-between.

In a Q-sort the number of cards can be varied as can the number of piles and the type of question (e.g. How I am now? How I used to be? How my partner sees me? How I would like to be?) so there are a potentially infinite number of variations. That, of course, is exactly as it should be for an idiographic psychologist because in his/her view there are ultimately as many different personalities as there are people.


From these examples we can see that the difference between a nomothetic and an idiographic approach is not just a question of what the psychologist wants to discover but also of the methods used. Experiments. correlation, psychometric testing and other quantitative methods are favoured from a nomothetic point of view. Case studies, informal interviews, unstructured observation and other qualitative methods are idiographic.

There are also broad differences between theoretical perspectives. Behaviorist, cognitive and biological psychologists tend to focus on discovering laws or establishing generalizations. The humanists are interested in the individual. As in so many other debates psychoanalysis is difficult to pin down. Thus it could be seen as nomothetic if one were to concentrate on Freud’s view of the psychic apparatus common to us all (id, ego, superego). On the other hand each patient represents a new challenge for therapy with a configuration of defense mechanisms that is all their own and an illness that derives from unique childhood experiences.

How to reference this article:

McLeod, S. A. (2007). Nomothetic idiographic debate. Retrieved from

Nomothetic Approach to Personality

This section reviews nomothetic approach. It brings together the ideas and perspectives as how personality is understood by trait theorists. It will also briefly touch upon how psychologists predict human behaviour using this approach.


Nomothetic Approach

Nomothetic view also known as ‘trait’ approach’ looks for universal laws of behaviour. Being able to predict behaviour is a mayor aim and outcome of this idea. Psychologists adopting this approach hold that ‘traits’ are source of human personality. A trait is assumed to be any enduring characteristic of an individual that is relatively stable and influence behaviour in a particular direction. Theorists adopting this approach believe that personality is consistent, largely inherited and determined by genetics and biochemistry of our brains. They argue that it is matter of biological functioning, fixed at birth if not before and that environmental factors, life's experiences and social influences have little or nothing to alter it.


Traits as personality determinants

Proponents of nomothetic approach claim that the above provides solid foundation to create instrument measures. Psychologists that see traits as major determinant of human behaviour identify set of traits along which all humans can be classified and compared to. They identify traits that are considered to characterise human personality. They hold that human beings share number of characteristics and that the study of each of these will shed more light on understanding similarities and differences among individuals. This can be demonstrated in the figure below which shows four personality types with trait characteristics.

To construct instrument measures that allow psychologists to develop scales, individual characteristics are grouped into clusters creating types. For example, trait associated with practicality and risks taking are found in extrovert type. The same retrospectively, quiet less sociable character would be associated with introvert type. Hence nomothetic approach involves categorising individuals in order to uncover the common causes of behaviour. Thus it allows psychologists to identify and classify personality according to recognisable characteristics.

Personality dimensions

There are big five key dimensions linked to human behaviour. These describe how people respond to stress, adjust to new environments or determine their interests. They focus to provide insight as how effectively an individual would be able to work with others, set up his goals or establish his identity and role. A research suggests that five basic dimensions underlie all others and encompass most of the significant variation in human personality. See these dimensions in the below model.

The first characteristic is defined as extroversion versus introversion. It measures the extent to which an individual is oriented to the outside world. The second trait refers to conscientiousness, that is, how an individual is organised, dependable or focused. Agreeableness is the third trait identified and measures the degree to which an individual is friendly, reliable or co-operative with others. The fourth trait covers emotional stability which taps on person’s ability to withstand stress. People that are emotionally stable are likely to be calm, secure and self-confident. The fifth dimension addresses openness to experience. Open personalities expose creativity, curiousness as opposed to person at the other end which may find comfort in the familiarity.


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