If we replace the homeless man with a child suffering from down syndrome. Orphaned, abandoned, or simply unwanted by his/her family. There is no chance that the killer could enter into a situation that would permit them to be killed, because down syndrome is something you have from birth or you don't have for your entire life. Society also prospers slightly in terms of natural selection and in that it no longer needs to support the "victim".
Should it be legal under a system of "Natural Law" for consenting families to murder a child because the child suffers from an undesireable genetic disorder like down syndrome? (Note: not under the existing mishmash system of law, but an "ideal" system of law based entirely on utilitarianism).
I'm going to assume that the answer to the above question is yes (if you can convince me that it's no, then the remainder of this post can be rejected). The current law does not permit this killing of people after birth. Why is this the case? It must be based on something non-empirical. What grounds are there for current law to accept these non-empirical considerations to support loss of rights for those who wish to kill their child and reject those proposed by the hypothetical person to support loss of rights for homosexual couples? Majority belief? Then surely Will is correct when he says.
I believe that there is no such thing as objective law. Law is just morality forced upon others by either force or by consent of those who are being governed. The closest thing we have to objective law is a law in which the majority agrees with the majority of the law
-Kev
And here is where I flip it on you and turn your assumed "yes" into a "no".
You make several assumptions that I can break in your little CRT, or Current reality tree for those who aren't in the know
For your question to come out with a "yes" you must assume ALL the following;
1) There is ever a condition underwhich a human child can be alive and not contribute something to the world
2) Human emotion can turn on the child and emotionally permit the killing of the child with no emotional or physical harm to the killer
3) The childs condition can be PERFECTLY diagnosed and can be PERFECTLY demonstrated
OR
1) Survival resources are scarce
Without any of those three assumptions, then killing that child becomes immediatly immoral under natural law OR utility theory.
If the child provides happiness to you, then you cannot kill it. If killing the child is morally reprehensible to you, then you cannot kill it. If the child provides value to the rest of the world, if you fear that the child is misdiagnosed and have hope that it may recover, then you cannot kill it ... and even if killing it is ok to you, if it may not be to the rest of the world.. therefore the rest of the world may kill (or punish) you in response.
If you kill that child and it is accepted that all children with this condition should be killed then you may have the fear that your next child may be misdiagnosed with this same condition and would be unjustly killed.
In other words, IF mankind as a whole saw no intrinsic value in a human life AND we have perfect information concerning the child then yes, utility theory and natural law would both say that the child should die.
Look at the animal world. Isn't that how things happen there?
HOWEVER, this is where the social contract comes into play. Because the social contract says that all human life has an intrinsic value (which is innately felt, in one degree or another, by all humans as part of our survival instinct anyways) and therefore should be preserved. In fact, it is one of the primary principles of the social contract.... all human life provides SOMETHING to society, be it labor, happiness, peace of mind, etc etc.
Therefore, even if that child has no intrinsic value to the parents the child DOES have value to society as a whole. The social contract forces that heartless family to consider the good of all of society and, therefore, not kill the child.
Now, the one big BUT that gets thrown into this, is if we assume there are not enough resources in the 'market' to provide survival for all life. In this case, the bottom must be trimmed off and if this hypothetical child is consuming resources that could be used to keep someone more valuable alive then the child should be killed under natural law.
Also, keep in mind, my point isn't that the government IS governed by natural law or utility theory. It's that the government SHOULD be governed by it and LARGELY is. There are a lot of exceptions you could dig up in law if you wanted to spend the time. But I think most of them are slowly getting changed over from a religious morality to a rational morality...