Enough advertising for Apple, I am still pecking away on a PC and a Blackberry... To take this another step, if you imagine you are at a social function you could expect to be asked politely (perhaps several times) WHAT you do: 'I am an airline pilot...' You might even occasionally be asked about HOW you do that: 'Well we train a lot, get a licence, beg for a first job...' But I doubt if anyone has asked you WHY you do it, unless your job is Chief Executioner or something. Actually it is the best question of all and likely to yield the most interesting answers - try asking someone.
In both aviation safety and one of its strongest influences, organisational culture, the same would be true. We know a lot about WHAT people do: fly aeroplanes, sell tickets, mend engines, clean floors; we know quite a lot about HOW they do it: procedures, manuals, policies, instructions; but crucially we have little understanding of WHY people do the things they do. After an accident we have lots of recorded flight data to tell us WHAT and to some extent HOW things went wrong but because most accidents include a significant element of human action or inaction it would be very useful to understand WHY they acted as they did.