Some people, like the late John Rawls, say that we should set aside our religious and philosophical disagreements – our “comprehensive doctrines,” he calls them -- for the sake of practical agreement.  Others say that we can’t do that, and that it’s futile to try.

Can we, or can’t we?  It depends on what you mean.

I can usually reach agreement about quite a few practical matters with an everyday materialistic atheist.  For example, he will probably agree with me that murder is wrong, even though I think God exists and he doesn’t, and even though he thinks matter is all there is but I don’t.  If this sort of thing weren’t possible, I don’t see how we could even live in the same society.

Notice, though, that this practical agreement isn’t philosophically or theologically neutral.  The very idea of a “right” and a “wrong” is itself a profound point of philosophy and theology, even if the other fellow doesn’t recognize the fact.  Very often, he doesn’t recognize it.  For example, sometimes people tell me they don’t see why there has to be a lawgiver for there to be a moral law, or why a materialist can’t have a conscience.

And I agree with them – in part.  A person doesn’t have a conscience just because he holds a theory which says that there is such a thing as conscience.  He can’t help having one, even if his theory can’t account for it.  It belongs to him as a human being.

Nevertheless, if his theory has no room for it, he has a problem.  If, as a matter of astronomical theory, I denied that there was a sun, I would still see light and dark, but I would be in an awkward position, for with no source of light, how there can even be a light and dark?  There shouldn’t be -- but there is!  How awkward.

Now if someone called the awkwardness of my view to my attention, I could do either of several things.  I could change my mind, admitting that there must be a source of light after all – or I could change in the other direction, deciding that since there isn’t any source of light, my perception of a difference between light and dark must be an illusion.

In the same way, if, as a matter of religion or metaphysics, I denied that there is a moral lawgiver, I may still experience the weight of moral law, like Raskolnikov.  If I didn’t acknowledge any authority of which conscience is the voice, I might still hear its voice.  And if I thought matter is all there is, I might still, despite myself, perceive a difference between right and wrong, both of which are nonmaterial.  My perceptions and experiences wouldn’t go away just because of my philosophy. 

But here too I face a choice.  I might try to make these perceptions and experiences go away.  For even if it is true that my having a conscience doesn’t depend on which theory I hold, it doesn’t follow that I have a well-formed conscience.  The fellow who says light and dark are illusory will probably blunder into all sorts of things that his eyes tell him to avoid.  The fellow who says right and wrong are illusory will probably allow himself all sorts of bad conduct that his conscience warns him against.

There is also the problem of what his conscience says.  If the classical theory of conscience is correct, then there are certain first principles we “can’t not know.”  For example, Thomas Aquinas maintains that deep down everyone really knows the wrong of murder.  But in the first place we may try to convince ourselves that we don’t really know what we know, for we humans are unusually capable of self-deception.  In the second place we may go badly wrong about the details.  For example, I may acknowledge the wrong of deliberately taking innocent human life, but say that you aren’t innocent because you’re descended from people who long ago took my ancestor’s land.  And in the third place, even if deep down I know that even that isn’t true, I may not allow myself to admit it.

Natural law is a fact, pressing upon us by its own weight, like gravity.  The theory comes afterward and explains it.  Unfortunately, this home truth doesn’t make it unimportant to have the theory.  Although people who don’t understand how it is with heavy objects may not often walk off the edges of cliffs, they may have a very hard time making buildings that don’t fall down – and although people who deny the natural law may not lose human society altogether, they will probably live wretchedly.

These difficulties have not been so great that people have never been able to form communities and live together, but the quality of the communities they form is another matter.  The Aztecs had law and government, but they also practiced the ritual murder of captives taken in war.  Modern societies which recognize what the Aztecs did as murder nevertheless cut themselves exceptions for the very old, the very young, and the very weak, and the cut-outs are getting bigger.  It isn’t that we can’t reach practical agreement.  The problem is that the agreements we reach are increasingly perverse.

So rather than asking whether we can set aside our religious and philosophical disagreements for the sake of practical agreement -- as though this were a yes-or-no question – we ought to ask how much religious and philosophical agreement about which matters is necessary for what kinds of practical agreement.

It may be that no abstract answer to this question is possible.  Can we reach practical agreement about this or about that?  Perhaps we can find out only by trying.

But what if one of the points of religious and philosophical disagreement is whether we even should try?  Let’s not suppose that religion and philosophy can simply be set aside.