I’ve read both OPAR and the Virtue of Selfishness, but I still don’t see how this makes ethics objective. Just as one can pursue life one can also pursue, say, pleasure. Why are the values required for life objective when the values required for pleasure are not? As this is a matter of choice, how does one motivate pursuing life as being more rational than pursuing pleasure?
It seems to me you are trying to say this: Since what makes something rational or irrational depend on the ultimate value you choose, then it seems impossible to say that some ultimate value is more rational another. After all, the ultimate value cannot, if it is truly the ultimate, cannot be justified by some other more ultimate value which makes it rational.
If this is what you are trying to say, then I answer by saying: “This is true, but so what? It does not follow from this that anyone is justified to pick whatever ultimate end he wants.” Why? Because what is the ultimate end is not anything one wants it to be. It can be identified as a fact, and it is life. Life is what’s ultimately what’s at stake for living organisms - not your pleasure, not your love, not your house, not your money, etc. And everything you desire and need depend on you living.
Further: Why is it desirable to be rational? Because it is good to be rational? Good? To whom and for what? The fact is that it is only good to be rational for living organisms (human beings to be exact) and only for the purpose of living. Outside this context, you are using the concept “value,” as a stolen concept.
How come? Well, you ignore or forget all the facts that makes something a value, when you just assume implicitly that rationality is something we should care about. But we should only care about it, if we have already chosen life as our ultimate value. Now, most people do not choose life explicitly. They do nevertheless choose it implicitly, as indicated by their (inconsistent) pro-life actions.
There is no reason to say that some ultimate end is more or less rational compared with some other so-called ultimate end. Because as I’ve already indicated, it is only for living organisms who pursue life, it makes sense to say that something is rational and therefore good, and vice versa. If you do not want to live, then it makes no difference to you whether you are rational or not.
It’s only in this context - the context of living organisms pursuing life - that this usage of the concept “rational” could be formed. Outside this context, there is no need to talk of something as rational or irrational. Thus, to choose life is not more rational than to choose death. The choice is not irrational either. It’s pre-rational.