“'Tis not contrary to reason to prefer the destruction of the whole world to the scratching of my finger. ‘Tis not contrary to reason for me to chuse my total ruin, to prevent the least uneasiness of an Indian or person wholly unknown to me. ‘Tis as little contrary to reason to prefer even my own acknowledg'd lesser good to my greater, and have a more ardent affection for the former than for the latter.”
David Hume
(2.3.3.6)
[snip]
"Hume famously closes the section of the Treatise that argues against moral rationalism by observing that other systems of moral philosophy, proceeding in the ordinary way of reasoning, at some point make an unremarked transition from premises linked only by “is” to propositions linked by “ought” (expressing a new relation) — a deduction that seems to Hume “altogether inconceivable ” (T3.1.1.27). Attention to this transition would “subvert all the vulgar systems of morality, and let us see, that the distinction of vice and virtue is not founded merely on the relations of objects, nor is perceiv'd by reason” (ibid.)
http://plato.stanford.edu/entries/hume-moral/
Cordially,
Hume was simply wrong. You can rely on a chosen authority or you can arrive at your own belifs based on the evidence available now. Again, Hume was very simply wrong.
With much admiration,