The argument from reason and free will. (This argument will probably be harder to follow than the others, so don’t worry if you don’t understand it all. But I put it in because it’s good to have a challenge that stretches your mind now and then and also because it’s a very important point about human nature, about who you are, and about how you are different from an animal. Many people are confused about this point today, and it’s important that you are not confused about it.) Our souls can perform two acts that are spiritual, not just physical; therefore, our souls must be spiritual. And what is spiritual is not mortal. Therefore our souls are immortal. We can know abstract eternal truths like “Justice is a virtue” or “2 + 2 = 4”, and we can freely choose between right and wrong. Animals cannot do those two things because they do not have spiritual souls. They have biological life, unlike rocks, and they have feelings, unlike plants—even some surprisingly human feelings like affection—and they have very clever instincts. But they don’t have reason or free will. Human thinking is rational understanding, and human choosing is free and morally responsible. Human thinking is not just sensation and imagination, and human willing is not just feeling and instinct. Put reason and free choice together and you get morality. Morality presupposes these two things: understanding right and wrong, and freely choosing between right and wrong. That is why we don’t just train humans, as we train dogs, and why we don’t preach to dogs, as we preach to humans. When the dog pees on the carpet, we don’t tell him to go to confession! And when we sin, we don’t just whine and slink away from our master. We repent and go to our Master. You can observe in yourself your power to do these two things that animals cannot do. First of all, take your ability to think rationally, beyond sensation and sensory imagination. You can both see and imagine the difference between a three-sided figure and a four-sided figure, and animals can too. But if you take a course in geometry, you can also understand that difference. And you can understand things you cannot imagine. You cannot imagine the difference between a thirty-three-sided figure and a thirty-four-sided figure, but you can understand it and calculate it. You can imagine the difference between a man and a woman, but you cannot imagine the difference between a just man and an unjust man. But you can understand it. You can also observe in yourself the second thing that raises you above animals: the difference between free will and animal instinct. When you see something flying through the air at your face, you close your eyes instinctively, just as an animal does. But when you see something you think you shouldn’t see, like the answers on the test paper of the classmate in front of you, you close your eyes deliberately and by free choice. Or else you look deliberately. You can choose to look or not to look, to cheat or not to cheat. A spiritual act can come only from a spiritual actor. A spiritual effect can come only from a spiritual cause. Rational thinking and free moral choosing are spiritual acts, so they must come from a spiritual cause—from a soul, not merely a body. (“ Spiritual” here means not-physical, not-material. It doesn’t mean religious.) Of course the soul is dependent on the body. It uses the body as an instrument. It uses the body’s brain as you use your computer. When your computer crashes, you can’t use it, and when your brain is damaged, you can’t think. But the brain is not the soul any more than your computer is you. However, the relation between the soul and the brain is not the same as the relation between you and your computer. The soul is the very life of the body and of the brain that is one of the body’s organs. You are not the very life of your computer.
The argument from God. If there is no life after death, there is no God, and you have to be an atheist. For if God exists, then immortality must exist also because of divine justice. Not everyone gets what they deserve in this life, and if there is no next life, then there is no justice in the end; and if justice does not have the last word, then a God of justice does not exist. Also, if God exists, then immortality exists because of God’s love. If you love someone, you want him to live. If even we selfish human beings want those people we love to live, how much more must God want this? Does God love your dear departed family member less than you do?
The argument from the intrinsic value of the person. (This is another “stretch” argument and another very important one because it’s about what kind of value you have as a person.) If death is the end, and there is no life after death, then people are treated like cars. You can replace your car, but you can’t replace your friend. If reality treats people like cars, then reality is immoral. And if reality is immoral, why take morality seriously? If the deepest moral values—the intrinsic value of persons—has no ground in reality; if this idea that persons are intrinsically valuable and ought to be loved as ends rather than used as means—if this idea is only our subjective feeling or desire, then there is no objectively real obligation to love people, to treat them as ends and as unique and irreplaceable. But you can understand this argument only if you love. Love opens your eyes. When you love someone, you get new eyes: you see something you never saw before. You see that the person you love has intrinsic value, unique value, irreplaceable value, absolute value rather than relative value. You see that this person—and every person—is not a means but an end. Pope John Paul II loved to quote this saying of the documents of Vatican II: “Man is the only creature in the universe that God willed for his own sake.” Love gives you Godlike eyes. You see this as a basic truth of morality: that we ought to love people, not use them, and to use things, not love them. And once you see that, the argument follows. Once you see people’s value, you see their immortality.