@fresco,
(well my reading of the whole argument, albeit from an extremely high level, is that Hume took aim at causality precisely to overthrow the various types of teleological and first-cause arguments which were the bread-and-butter of all the established philosophy of his day. This is why he was so enthusiastically received by the Enlightenment thinkers. Good empiricist that he was, he was determined to show that all our knowledge comes about not through some
a priori intuition of the type espoused by Platonists, Liebniz, and the rest of those obscurantists, but from good, ol' fashioned Scottish common sense. That is why he has been so enduringly popular amongst your crusty scientific skeptics, who quote him with the hushed reverence formerly accorded to Aristotle.
The unfortunate thing for Hume (and the other empiricists) is that Kant definitively showed that in some very important respects 'the object conforms to our perception', and not visca versa. In fact Kant did a great job in overturning the extreme skepticism that Hume deployed in his attempt to discredit anything faintly metaphysical, and it is Kant who has had the enduring legacy, which is stronger than ever in cognitivism, constructivism and many of the important perspectives of post-modernism.)