"eliminating the weak from the gene pool will result in a healthier population"
Sorry to say, but this is incorrect.
It should be:"eliminating the weak from the gene pool will result in a healthier population
under current circumstances".
The difference is incredibly important to evolution and genetic variation (even the seemingly weak ones) is a big part of the survival mechanism of a species.
It is, as we have found out in biology over the past decennia, the core flaw with the eugenic line of thought.
Yes, that's exactly the idea I've elaborated in the following sentences, and also other parts of the topic. The reason I gave the eugenics example is because its premise is only correct in a very narrow context. Also, what you say is the less important flaw of eugenics. Not only it's "temporary" as you said, it's
you who define health. So descriptive ignorance and normative relativity are two different things. Even if you could measure weakness in all possible circumstances, it would still be your measure.
To elaborate, imagine that Alice's view as the goal of humanity is epistemological enlightenment. And Bob's is happiness of individuals. And Carlos thinks it's survival of humans as a race. What would be their ideas of the ideal environment for a human being? Or even, are their idea of a human being the same? What would they think about cloning or eugenics? What about economical structure, social structure? How would they compare the value of life to other values? So on and so forth...