Via Justin Taylor, here’s Peter Kreeft with a very thorough, very well-reasoned, and very long argument against abortion. It’s way smarter than anything you’ve heard any politician say on the subject for the last, oh, let’s say fifty years. A taste:
7. Moral Arguments Presuppose Metaphysical Principles
The main reason people deny that morality must (or even can) be based on metaphysics is that they say we don’t really know what reality is, we only have opinions. They point out, correctly, that we are less agreed about morality than science or everyday practical facts. We don’t differ about whether the sun is a planet or whether we need to eat to live, but we do differ about things like abortion, capital punishment, and animal rights.
But the very fact that we argue about it—a fact the skeptic points to as a reason for skepticism—is a refutation of skepticism. We don’t argue about how we feel, about subjective things. You never hear an argument like this: “I feel great.” “No, I feel terrible.”
For instance, both pro-lifers and pro-choicers usually agree that it’s wrong to kill innocent persons against their will and it’s not wrong to kill parts of persons, like cancer cells. And both the proponents and opponents of capital punishment usually agree that human life is of great value; that’s why the proponent wants to protect the life of the innocent by executing murderers and why the opponent wants to protect the life even of the murderer. They radically disagree about how to apply the principle that human life is valuable, but they both assume and appeal to that same principle.
9. Either All Have Rights or Only Some Have Rights
The reason all human beings have human rights is that all human beings are human. Only two philosophies of human rights are logically possible. Either all human beings have rights, or only some human beings have rights. There is no third possibility. But the reason for believing either one of these two possibilities is even more important than which one you believe.
Suppose you believe that all human beings have rights. Do you believe that all human beings have rights because they are human beings? Do you dare to do metaphysics? Are human rights “inalienable” because they are inherent in human nature, in the human essence, in the human being, in what humans, in fact, are? Or do you believe that all human beings have rights because some human beings say so—because some human wills have declared that all human beings have rights? If it’s the first reason, you are secure against tyranny and usurpation of rights. If it’s the second reason, you are not. For human nature doesn’t change, but human wills do. The same human wills that say today that all humans have rights may well say tomorrow that only some have rights.
I think you can see where he’s going with this, and he does a good job of getting there.