'Is & Ought' in David Hume

[Pyrrho]

The first thing I want to say is that you are going on to another topic, which is, what is the basis for morality?  I would rather have that discussion in another thread, and keep this one about the question of whether moral principles can be derived from matters of fact, and what Hume had to say about that.

However, I do not want to leave the following without comment, so....

I have no difficulty in translating descriptive statements into prescriptive ones, for example,  such as:

Every human being desires a modicum of happiness (including but not limited to pleasure, health, friendship, etc.). When there are opportunities to fulfill such desires, human beings tend towards them. Therefore, every human being acts to fulfill his or her conception of happiness.

This means, essentially, if you want to possess a state of happiness (and everyone does), then you ought to pursue that which stands to actualize what it is you want.

Your hypothetical is a practical matter, rather than a matter of morality.  To borrow an expression from Kant, you have a hypothetical imperative, not something that applies categorically to everyone.  Whenever you have an 'if-then' kind of statement, a hypothetical statement, it only applies to those for whom the antecedent is relevant.  To illustrate how this sort of statement is not providing moral guidance, consider the following example:

If you want to molest little children, then you ought to say things like, "hey little girl, want some candy?" to lure them in.

This is all about means to ends, and does not provide an end; the end is presupposed (in the antecedent, the part connected to the 'if' in the sentence).  And it is something to be ignored by anyone who does not have any interest in the antecedent.  Notice, this is not something that is about morality, but about achieving a particular goal.

With morality, one has statements like:

One ought not kill people for pleasure.

Notice, it is not a hypothetical, and is not merely giving practical advice on how to achieve a particular goal one might have.

According to Hume, such things are based upon certain types of feelings that people have, and that are nearly universal in that nearly everyone feels that way.   With my particular example, you will likely find very few people who seriously feel like it is okay for people to kill other people for pleasure.  There is more to it than that (it is not merely a matter of near-universal agreement; it is only some types of feelings that are relevant to morality), but I don't want this thread to deal with that issue; here, though is a start for someone interested in this matter.  See also this.

Clearly, our conceptions about what brings about maximum happiness, and the actions that one can take to fulfill this want, form much of the debate. I believe one can be wrong about what it is they think maximum happiness is and entails, but establishing the truth or falsity of a given conception of maximum happiness in a universal sense is much harder to do since in reality we are dealing with particular persons in particular situations. That said, I believe it can be done, and even if one denies this, the affirmation or denial still requires a context of an absolute objective---that either some notion of the good life as an end applies equally to all or conversely that it only applies to each individual relative to their own goals. (I.e. you cannot deny absolutes without doing so absolutely, and if your denial is only true relative to yourself, there's no reason anyone else must agree).

That sounds a bit like John Stuart Mill's position for the basis of morality.  If you want to argue about that, we can do so in another thread.