One way of defining if someone is abnormal is by asking whether they can function (do the basic things needed in day-to-day life) to a reasonable standard.
For example someone might be considered abnormal if they are so paranoid that they often can’t leave their homes, this means they aren’t functioning adequately so have an abnormality.
Conversely, you might be paranoid, but that doesn’t prevent you from living a reasonably normal life, you can still do the things needed every day, so this definition says you are not abnormal.
– Who judges what is “functioning adequately”? – In some cases, the person with a possible abnormality says they do themselves as they feel “different” and unable to cope, so they class themselves as abnormal. However, at other times someone with an abnormality often wont think anything is abnormal about them at all, here other people might then label them as abnormal. So who should decide, the person or everyone else who can see it?
– Adaptive or maladaptive? – Some “abnormal” behaviour could not in fact be caused by being abnormal, but by the person using his different behaviour to help them cope. For example, someone might appear stressed a lot, so act with the symptoms of stress. This then causes those around him to take extra care and look after him, helping him cope with the stress. So is this something that is bad (maladaptive) or a helpful way of overcoming a problem (maladaptive)?
– Cultural Relativism – Different cultures have different ideas of what not functioning adequately would be. What one culture perceives as a failure to function, another might see as perfectly normal.