Hume rejects the view that ‘cause’ is a priori. Can you describe: his account of what a cause is how we acquire the concept of cause what, if any, role it plays in the acquisition of knowledge or belief

  Hume's account of empirical knowledge, and how it is not obtained, has raised some troubling questions. His theory of the mind describes a collection of ideas and impressions related by resemblance, contiguity and cause and effect.

It is cause and effect that leads us to inferring things about the outside, empirical world beyond our immediate senses. What Hume argues is that knowledge cannot be found beyond our immediate senses.

Hume's first denial about what knowledge can be is that mathematical or logical reasoning has any place in matters of fact or empirical  knowledge  From  what has  become  known  as   Hume's fork, he has divided what a mind can contemplate into relations of ideas and matters of fact. Logical reasoning has been   pigeonholed  into  relations  of  ideas  and  so are nothing to do with the empirical world.

His argument for rejecting 'cause' as a priori is that a matter of fact can  be denied  and not be logically indefensible. The sun may not rise tomorrow is not logically false. He also argues that that the effect  cannot  be  logically  reasoned   from  the cause.   It  only   comes  from experience. Adam would not know water could drown him from reasoning about water alone.

If cause is not inate then does it come from the senses? Hume's  second denial is   that it does not come from the senses. There is no observable force between cause and effect. However the mind feels there is a force between the two,   if only metaphysical.

Hume  explains   that cause and effect are just constant conjunctions of objects or events. They always occur together. This is Hume's   logical  definitions   of cause.   It   has   another clause that states that if the following event did not occur, then the preceding event did not exist.

Hume also considers a psychological definition of cause to answer  the  feeling in the mind that there is a cause. He believed that cause is a feature of human thought alone. It is part of our psychology and not 'out there' in the physical world.

So  we   acquire  the   concept  of   cause  by   believing  there   is a 'necessary connexion' between events. When two objects or events are constantly  conjoined the   idea   of   cause   occurs to the observer after repeated observations of the conjunction. The experience of repeated observations soon forms into habits and custom. The concept of cause soon becomes subsumed into custom.

The concept of cause may be the only way man can infer things beyond our  sense impressions.   For   the   business   of  living   Hume  agrees   that  inference   is necessary. It is part of our psychology.

Hume's third denial is that   we  can  never  be   justified  in   making  factual inferences   which   carry  us   beyond  the   sensual evidence of past and present observations. We are making a great presumption when we assume that the   future will  be   like  the   past.  This   is  a problem of induction, a logical process central  to   scientific  observation   and  hypothesis   making.  If  continual observation   and inferences as to future behaviour of events cannot become fact then where does this leave knowledge of the outside world?

Hume was concerned with placing human behaviour as a central natural philosophy or 'moral philosophy'. To this end he believed that humanity had   to   act   upon something   in  order   to  get on with the business of living, and this could be determined.

It is belief that enables mankind to move beyond immediate sensual  experience. But what is belief? Hume suggests that it is a deeper, more forceful feeling or sentiment.

What  Hume   has left us with are no hard facts or the ability to obtain certain knowledge of the empirical world, only feelings and sentiments.   Knowledge  may well   be  defined   in  terms of belief, and left to prove facts under continual critical   examination.  This   may  be  the  dynamic   needed  for   research  and improvement   of   mankind's  inferences   about the external world, rather than a negation of all things believed to be true about matters of fact.

There are problems with Hume's account of cause. A constant conjunction can  be just   a  coincidence. What is just coincidence and what is cause and effect? It is not beyond man to attribute a cause to two events that  are   not  constantly conjoined.  When does custom and habit 'kick in'. How many times do two objects or events have to be observed before  it   becomes  part   of  man-kinds'   or  the individual's   concept of cause and effect? How is the concept conveyed from the individual to others that have not  had  the  experience  of   observation.  The logical   definition's  second   clause  is   implausible. In an observation A/B there may be events 'B' where there is no 'A'.

Hume dismissed extreme scepticism by referring to the 'business in hand'. Human beings had to infer   things   from   their  surroundings   to   survive.  What the sceptics   would   argue  is   that  this does not answer the problem of knowledge itself. By exposing the problem of induction they would thank Hume for contributing  another   weapon in their armoury. Hume has, however, provided the dynamic for what knowledge could only be - a set of beliefs.   As mankind need inference  to   survive,  it   also  needs   to  question   those  inferences   when observations about the empirical world can change.

Course Notes.

Hume, An Enquiry Concerning Human Understanding, Ed. E Steinberg, Hackett Publishing Co.

A.J.Ayer,(1980),Hume, O.U.P. especially Chapter 4 - Cause and Effect.