I've given this some thought as well. Like most ideas, there are fundamentally good intents underpinning it.
I think the problem is that we don't know what traits to select for. By favoring one trait, you neglect another.
Tall, seemingly healthy people, can easily become people with back problems.
Lean people with high metabolism, can easily be casualties of a food shortage.
People who have a very strong immune system, can easily become victims of autoimmune diseases.
Brave, confident people, can easily become reckless.
There's a balance to most things, and there's often non-obvious dimensions to it.
If you look into selective animal breeding, you'll often see a decline. Comparing contemporary dog breeds to 100 year old pictures (you can google that), is both interesting and depressing. Most breeds have some decline, and seeing them side by side you'll see that many contemporary breeds are best described as deformed.
The strongest breeds with the least health problems, and longest lifespans are mostly mixed breeds, or very old breeds shaped by their environment.
There's also the question about how to do eugenics, practically.
Congratulations, you've been selected for the national breeding program.
You are hereby directed to appear before the designated authority on the date and time specified for reproduction.
Failure to appear or otherwise comply with this notice may result in:
- Additional administrative fees
- Monetary penalties
- Further enforcement action as permitted under governing regulations.
Some people born with birth-defects have been inspiration for other medical advances and technological advances that have been useful for other things... and without those people being born, many of those developments might never have happened. "Necessity is the mother of invention" or so the saying goes.
This is true, but it's a poor argument. The Dachau hypothermia experiments also yielded very valuable scientific data, which I think we ought to preserve and use. It's however not a defense for exposing people to similar suffering in the future.
We also have a lot of art (paintings, music, poetry, etc.) coming from people with various mental health issues that we likely wouldn't have ever gotten otherwise.
This is the same argument, but worse.
I get what you mean, but in context it becomes a defense for allowing future suffering - some people must suffer and die horrendously, for the rest of us to have art. It's just not a good tradeoff.