Untestable and subjective concepts = As with Freud’s psychodynamic approach, humanism suffers from a lack of empirical evidence and no possibility of systematically observing and measuring the processes which it describes. Self-actualisation cannot be objectively measured, due to individual differences and a lack of a universal measuring scale. Similarly, congruence may also be up to personal judgement, especially as opinions of whether one has is their ‘ideal self’ will differ. This does little to improve the scientific credibility of both humanism and Psychology.