Deviation from ideal mental health:
this definition states that abnormality is the absence of wellbeing. Jahoda came up with a set of criteria that define ideal mental health;
self-actualisation - being able to fulfil your potential
stress - need to be able to resist stress
identity - positive attitudes / self esteem
autonomy - control over your own life
accurate perception of reality - not hallucinating
mastery of the environment - being able to handle change
if you do not meet all these criteria, then you are classed as abnormal. For example, someone with depression may not have positive attitudes about themselves