Good God, man! Our capacity to reason is the only justification for our rights. A horse can't reason, so we own horses and use them for brute labor. We slaughter and eat cattle. We catch fish and chop them up and can them for food. All this because they can't reason so they have no rights -- unlike humans.
I hope you don't mean this literally. There are millions of humans without the innate capacity to reason. Not to mention those who are too young to have developed it.
Sorry, Patrick. I missed your post. I disagree. Our humanity is the justification for our rights. I believe idiots have basic rights, I'm afraid.