The Fallacy of Personality Tests


In management, there has been a proliferation of interest towards the means to predict success in managerial roles. The attraction towards a variety of personality tests has led to a deviation away from performance metrics as the true measure of management ability. The assumption that these evaluations predict performance in management lacks any empirical evidence despite many attempts in literature to prove their worth.

In order to discredit the value of tests that measure potential we must first explore the illogical nature of its assumptions. The problem originates from the abstraction that is ‘potential’. The concept assumes that there is an entity behind an action. The words used to describe this entity have changed throughout the ages including that of ‘soul’, ‘psyche’, and ‘mind’. The ‘mind’ is a construct which origins can be traced back to Homer and equates to his natural concept of concrete noun of physical ‘breath’. The concrete noun 'breath' being a physical object changed in meaning through time. This can be attributed to Plato's work which added a metaphysical universe that is not available to sense data. The transition of the breath into the soul and then into the mind remained popular as the Christian religion embraced these concepts. Therefore, the existence of the mind or soul lacks any real substance but is instead an inversion of language. If it is immaterial it cannot be measured. Objective measurement is the basis of all real scientific study.

Looking beyond the origins of the word ‘mind’, the search for the existence of the mind in science has never produced any real evidence. The idea that we have thoughts that are stored in our brain has never been empirically established in any field. Even with today’s technological progress in brain imaging we are unable to prove the existence of a mind. This concept can be extended to other abstractions such as ‘personality’ and potential. Therefore, ‘potential’ is as immeasurable as any other abstraction and has no value in making predictions.

The more objective measure is performance. Performance can be measured in a number of ways which can be directly related to a person’s actions. Producing results through various means is the primary purpose of a manager because results in the form of metrics such as profit, revenue, cost efficiency and productivity are the output of each individual employee input – as Peter Drucker would advocate that such metrics are an essential condition for the company’s continued existence and sustainability.

The notion that performance being a key element in management can be supported by the world view of Homer that describes that one is the sum of their actions – in fact that there is no ‘’one” behind the action. The concept of “potential”, being an abstraction, is intangible and therefore would not equate to any worth in a Homeric philosophy. Hence, Drucker’s central philosophy that a manager’s job is to prepare people to perform reflects this Homeric ideal.

An important point to understand is how performance is tested. Looking at one’s past performance in preparation for a future role can be argued as assessing their ‘’potential’’ for the future role. It is only when a manager is already in the role that performance is truly tested. This real time testing is a true representation of the effectiveness of the manager because it is testing the person in the correct context. A good performance test will effectively determine their suitability to continue. The alternative performance tests involve looking at things such as one’s past experience. This is a better predictor of suitability for a role however still assesses ‘’potential’’ rather than ‘’performance’’. This type of potential is far more useful; however, than those based on personality tests.

The famous Myers-Briggs personality tests are designed to determine one’s personality type from which certain personality ‘traits’ can be determined. These traits supposedly give a manager a prediction of an employees’ likely potential in a particular role. Descriptions such as ‘’efficient’’, ’’intellectual’’, ‘’action-orientated’’ and ‘’analytical’’ are examples of certain personality traits. There has never been any evidence to support the test’s use to predict performance in any organisation. Therefore, the idea that people with extraverted personalities perform better in certain roles when compared to people introverted personalities is unsupported.




The existence of a ‘’trait’’ presupposes that one inherits these qualities from their parents. This leads to a dilemma where all accountability is lost. The ridding of responsibility due to an uncontrollable predetermination is contrary to existential philosophy. Predetermination leads to predictability from whatever personality one may have. The construct of management would therefore be superfluous since all action can be predicted based on potential and all responsibility for actions whether positive or negative in nature cannot be accredited to the individual but rather their inheritance. Obviously this is not the case and therefore all that is left is performance or behaviour based testing.

Performance testing is an extension of the concept of technical ability because it looks at a person’s skills rather than value based judgements which are more closely aligned to the concept of ‘’potential’’ or ‘’charisma’’. The latter concepts move towards an illogical basis for following or choosing a manager. Subsequently, methods that delve into these notions include interviews. Assessing an aspiring manager using this technique gives an employer an idea of how they will respond under pressure. This real time assessment of behaviour in certain situations has remained popular business; however this method of testing fails to be completely reliable as there is countless evidence that those who do well at interview don’t necessarily translate the same success in their managerial roles.

Another way that potential is often tested is through IQ tests. These attempt to make predictions of a candidates ability to perform based on the supposed correlation of IQ with performance. This notion is true to a certain extent, however has been shown to provide diminishing returns as one’s IQ reaches a level which shows a tendency for the manager to lose interest in an environment that is not intellectually stimulating. This type or performance testing is far removed from the roles requirements however still provide a better predictor than that of personality testing.

The idea that our behaviour is a reflection of the mind is an argument that supports the claim that psychology is a science. Conscious mind versus unconscious mind, regressed and egressed thoughts are ideas that have stemmed from Sigmund Freud’s popular theories. The interpretation of behaviour as symbolic is the crux of Freud’s life work. The method in which psychologists claim to study an immaterial psyche is through their understanding that the behaviour is a direct expression of the mind but is disguised with as metaphors. This creates an issue that psychology is using human behaviour as a connection to the mind and therefore can be studied empirically. Freud's work has been one of the most influential of all of psychology with much of his work still supported today. Freud deals with the unconscious mind and offers an explanation of the inner self through interpretation of dreams. Freud's theory lacks any scientific evidence because there has never been proof that people have one singular driving force that dictates behaviour. Herein lies the problem that where there is a theory that is untestable and hence unfalsifiable. These are necessary characteristics of scientific study. Therefore even Freud's work, as influential as it has been, is not a science. This is an illogical stance as it requires a material mind to exist in order for it to project disguised behaviour.


The proposition that the mind exists fails the tests of empirical facts and logic. The remaining criteria is a ‘faith’ based approach and is the weakest of the three. Freud claims that he simply observes human behaviour and comes up with a pragmatic explanation. This is clearly not a science but a personal opinion that cannot be tested.

Eysenck’s personality questionnaire looks to find personality traits which are divided into introvert, extravert, emotional and stable. Managers have used this test to make predictions despite Eysenck’s strong advice against such a use. Theoretically, this test can be used to find those who are risk takers, irresponsible and have low self-esteem. This questionnaire has produced the most reliable results over the last few decades and yet lacks strong predictability when used in a real world setting. The correlations are statistically significant, yet its predictive powers are minimal. Therefore, harder, more objective data through the assessment through true performance metrics are more robust than even the best personality tests.

Drucker is strongly against the use of staffing to suit personality (even if it exists). The argument lies on the point that jobs are not created by nature or by God and therefore do not follow are predictable course. Hence, consider an organisation that was to create a job based on a specific personality type - it would undoubtedly fail in the long term as the job would defeat the employee. People are not infinitely predictable and therefore cannot be aligned perfectly into a particular role. Therefore, the assessment of potential for a particular role, even if in a point in time a candidate seems to be a perfect fit, would ultimately be redundant.  Drucker advises to instead look at performance based testing during the time that the manager is already in the role because it has the tendency to isolate individual strengths in particular areas.

The pragmatism required in management has led to an obsession in finding whatever tools and methods to have a competitive advantage in the environment. This can often result in a company spending large amounts of money in such tools for the mere fact that it is popular at the time. Performance testing in management, particularly those that assess employees whilst in their respective roles, are more robust and reliable than tests that assess potential. The foundation for this argument derives from the lack of logic in the notion of personality, and also the lack of empirical evidence that looks at the predictive power of such testing methods.