Two things fill the mind with ever-increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them: the starry heavens above me and the moral law within me.—Immanuel Kant

If you’ve been with me for a while, you’ve probably noticed that I love astronomy. The universe beyond is indescribably enormous, beautiful and humbling. When we look into the night sky, we are looking into the past. Actually we are looking into many pasts, for each star so far away that its light takes anywhere from a few years to millions of years to reach us. Each star you see comes from a different point of the past.

Think about that for a few minutes.

Today, instead of looking outward, I want to look inward. How is it possible that we, bits of flesh trapped in space and time, can think about what is right and what is wrong?

Is it even possible for us to know such things? Is the distinction of right and wrong “real” or is it simply a human construction, something we’ve made up?

Take a minute to convince yourself that this is a real question.

Think about the question of whether right and wrong are even real things—somehow of this world and not just of our invention. Imagine that you want to do something. Something simple like eat that apple that is sitting on your counter. Imagine further that instead of just grabbing the apple and munching away, you ask yourself if you should eat the apple. Does the situation even make sense?

I think it makes sense to ask if you should eat the apple. You can consider reasons for eating (or not eating) it.

Adam and Eve

But does the question “should I eat this apple” even make sense? Of course it does. And the fact that it makes sense illustrates something about human reasoning. We can’t even begin to ask this question without recognizing that it is (at least in principle) answerable. It doesn’t follow that you can always find the answer; but it does follow that the question makes sense. And that’s the interesting thing. Because you are able to ask the question intelligibly, you know that “should” questions are intelligible.

Now you can interpret “should” many ways here. It could be a matter of prudence: I’ll need the apple later. Or it could be a matter of taste: I don’t like that kind of apple. Or it could be a matter of right and wrong: That apple belongs to Eve and I shouldn’t take it without asking. Or something else.

But look where we are again. Just by looking inside ourselves, we find ourselves discovering something that is true and has application beyond our mere mortal selves.

And we can go further. Our small, finite minds can ask moral questions of deep and lasting significance. Should we help strangers? Is sharing the right thing to do? Can I be good by being selfish? What kind of society is good? Why do I think that all people are created equally?

Don’t answer these if you don’t want to. But take some time to experience how amazing it is that you can think about ethical principles with infinite consequences. And how you can be sure that they are meaningful, even if you can’t be sure that you’ve got the right answers. For today or forever.