Must Humanists Be Naturalists?

Stephen Law

Are secular humanists obliged to sign up to naturalism? Should we define humanism (or secular humanism, as some prefer to call it in the United States) as involving a commitment to naturalism? Many humanists often define humanism that way, of course. However, I think defining humanism so that naturalism becomes a tenet of humanism is strategically a big mistake.

Here’s my preferred characterization of humanism from my Very Short Introduction to Humanism (Oxford University Press, 2011):

  1. Secular humanists place particular emphasis on the role of science and reason.
  2. Humanists are atheists. They do not sign up to belief in a god or gods.
  3. Humanists suppose that this is very probably the only life we have.
  4. Humanists usually believe in the existence and importance of moral value.
  5. Humanists emphasize our individual moral autonomy and responsibility.
  6. Humanists are political secularists in the sense that they favor an open, democratic society and believe the state should take a neutral stance on religion.
  7. Humanists believe that we can enjoy significant, meaningful lives even if there is no God and whether or not we happen to be religious.

See? No mention of naturalism. The seven issues above are those I think those of us who campaign under the banner of “humanism” should be focused on. Now, no doubt many who are humanists in the above sense are also committed to naturalism. And I certainly don’t want to dissuade anyone from signing up to naturalism if they wish. Indeed, I lean toward naturalism myself—despite my not wishing to firmly commit to it. But signing up to naturalism should not be required of secular humanists. It should merely be an option. Here are two reasons:

  1. There are plenty of people whom we should be welcoming to secular humanism who will be pointlessly excluded by the requirement that they sign up to naturalism.
  2. Insisting on naturalism generates an entirely pointless hostage to fortune in debates with theists and other religious persons.

I’ll start with the first reason. I’m lukewarm about naturalism because I am often unsure what the term is supposed to mean, particularly as used by humanists. Indeed, naturalism is a notoriously difficult term to define philosophically.

It’s popular, for example, to characterize naturalism as the rejection of the supernatural. But then what is the supernatural? If our answer is: “that which isn’t natural,” we have produced a wholly uninformative circle of definitions.

So what is the natural, then? The material? The physical? The spatio-temporal? All of these versions of naturalism face significant challenges. In particular, philosophers notoriously have struggled to find a way to accommodate the three m’s—minds, morals, and mathematics—within a purely materialist or physicalist framework.

Let’s start with mathematics. I believe a majority of professional mathematicians are inclined toward mathematical Platonism/realism—the view that mathematics describes a mathematical realm that is nonnatural. According to the mathematical Platonist, 2 + 2 = 4 is made true by a fact concerning how things stand in this nonnatural realm.

Philosophers have also struggled to accommodate, within the empirically observable world, truthmakers for moral claims. What makes “killing is wrong” true? Not, it seems, facts of the sort that observation of the natural world might reveal. Notoriously, such observations reveal facts only about what is the case, whereas moral claims concern what one ought or ought not to do. And it seems one can never rationally support an ought conclusion using only is claims. Hume’s famous is-ought “gap” seems, on the face of it, to entail that no purely natural fact is going to be capable of making true such moral judgments. This inclines at least some philosophers toward the view that we will have to look, then, toward a realm of nonnatural moral facts if our moral judgments are to be objectively true.

Consciousness is also notoriously philosophically baffling. How do we accommodate our inner realm of subjective experience—what it’s like to be a conscious, experiencing subject from the inside, as it were—within a wholly naturalistic framework?

I don’t know how to solve any of these three perennial puzzles: a puzzle about math, a puzzle about morals, and a puzzle about minds. In fact, these puzzles are part of what leads me to be somewhat guarded about naturalism. And I am not the only one. A 2009 Philpapers survey of professional philosophers and postgraduates revealed that only about half sign up to or lean toward naturalism. And that is not, note, because they are theists. Fewer than 15 percent of philosophers sign up to or lean toward theism.

So around 35 percent of philosophers are neither theists nor wedded to naturalism. Should these folk—myself included—be allowed into the humanist club? Of course we should. Make signing up to naturalism a requirement, on the other hand, and fully 35 percent of philosophers who might otherwise belong to the humanist brotherhood are effectively excluded—including me. And of course the naturalism requirement also requires humanists to exclude all those mathematicians who—while not believing in God and in no doubt in many cases signing up to my seven other principles—lean toward mathematical Platonism.

Excluding such people is, surely, a huge strategic mistake. That’s my first reason for not making naturalism a tenet of humanism. What about my other objection—that making naturalism a tenet of humanism creates an entirely pointless hostage to fortune in debates?

Well, once humanism is thus defined, it is sufficient for critics to refute humanism that they refute naturalism. And naturalism isn’t that easy to defend. Do you have philosophically bomb-proof responses to the above challenges to accommodate math, morals, and minds with a wholly naturalistic framework? I don’t. Once humanism is defined as requiring naturalism, all a theist has to do to rout humanists is to fire off these kinds of challenges and watch his or her humanist opponent struggle. At the very least, the audience is likely to come away with the impression that the debate ended up “all square,” with neither side having scored a decisive victory.

Now why give our intellectual opponents such a gift? Why force ourselves to defend what we will certainly struggle to defend and what we do not even need to defend? By making naturalism a tenet of humanism, we allow such religious apologists to, at the very least, get us secular humanists needlessly bogged down in an irrelevant philosophical sideshow.

We can sign up to atheism, political secularism, and all the rest without hitching our wagon to naturalism. It’s your option to defend and argue for naturalism if you wish. But don’t needlessly saddle the entire humanist movement with an obligation to do so.

In my opinion, in response to the Christian apologist’s standard debate-tactic question: “But how does your atheistic, naturalistic worldview accommodate consciousness, mathematical truth, and moral value?” We secular humanists should not attempt to defend naturalism but should just shrug and say: “Straw-man fallacy. Even if your objections successfully establish that naturalism is false, that leaves both my atheism and my secular humanism entirely unscathed. What are your arguments against atheism and secular humanism?” Say that, and watch your opponent panic with the realization that you’ve just taken most of his or her ammunition away.

To finish, let me make a couple of clarifications.

Philosophical vs. Methodological Naturalism

First, it’s worth distinguishing methodological naturalism from philosophical naturalism. Philosophical naturalism is the view that there is only “the natural” (whatever that is, exactly). Methodological naturalism is typically characterized as the view that science should work on the assumption that there is only the natural. Scientists shouldn’t invoke gods, ghosts, spirit beings, and other nonnatural woo in providing explanations. Thus, something like intelligent design/creationism is automatically ruled out as a scientific theory because it invokes a cosmic, supernatural intelligence to account for the supposedly “fine-tuned” character of our universe and/or the supposedly “irreducibly complex” biological phenomena.

Perhaps you think that, for the reasons I give, humanists should avoid signing up to philosophical naturalism but can and should at least sign up to methodological naturalism. I think that, too, is a mistake. We should reject methodological naturalism, thus understood.

Note, first of all, that scientists can and do investigate supernatural claims all the time. They are, and should be, prepared to consider and test supernatural hypotheses. Now of course, when they investigate the supernatural, scientists often come up with not just an absence of evidence for supernatural phenomena but evidence of the absence of such phenomena. Consider the huge scientific investigations into the power of petitionary prayer on heart patients, for example—which yielded good scientific evidence that prayer doesn’t work in that way.

However, scientists could conceivably come up with good evidence for various supernatural claims. They could turn up good evidence that some people have memories of past lives and thus have been reincarnated, for example. Or they might yet turn up good evidence that, say, Christian petitionary prayer works. We can’t rule out these possibilities from the comfort of our armchairs. Yet ruling out, from the comfort of one’s armchair, even the possibility of there being good scientific evidence for such claims is precisely what methodological naturalism does.

At this point, some hard-line methodological naturalists may insist that were such evidence to turn up, then effective petitionary prayer and past lives would then qualify as “natural.” If there’s scientific evidence for X, then X is, after all, natural. But this is semantic sleight-of-hand. Notice that even, say, intelligent design/creationism can now fall under the umbrella of “naturalism” if we turn up scientific evidence for it. What is it that methodological naturalism says can’t be posited by scientists? The answer, now, is: Nothing.

Naturalism and Scientific Woo-Skepticism

Second, it’s worth clarifying that, of course, many humanists are skeptical about woo claims, no doubt justifiably. Now, if naturalism just means adopting a scientifically skeptical attitude regarding woo claims—the attitude that such claims should not be accepted without good scientific evidence—well then, shouldn’t humanists at least be required to sign up to that? After all, even those philosophers and mathematicians who are unconvinced by naturalism will in many cases express just this sort of skepticism about fairies, ghosts, psychic powers, and so on.

I think that, insofar as humanists sign up to my first feature of humanism, secular humanists place particular emphasis on the role of science and reason; we probably should not count as a “humanist” someone who believes in a variety of woo on the basis of flimsy anecdotal evidence and casually dismisses the science. A commitment to framing our beliefs in light of the best scientific evidence is a requirement.

On the other hand, I don’t think that one must necessarily reject all woo claims, irrespective of what the scientific evidence might suggest, in order to qualify as a humanist.

Suppose it turns out that some people really do have psychic powers. Suppose that were to become scientifically well-established. Would humanism then be refuted? Not as far as I am concerned. Of course, most secular humanists will be mightily surprised if it turned out that psychic powers are real. But I don’t think such a discovery would spell doom for secular humanism per se, because I think secular humanism’s proper focus is elsewhere.

To sum up: let’s not characterize (secular) humanism as involving naturalism—it’s a pointless hostage to fortune and ends up excluding many who might usefully be our allies.

Stephen Law

Stephen Law is a lecturer in philosophy at Heythrop College, University of London.

He is the editor of Think, the author of numerous articles and books, and a debater of apologists and theologians. He has a blog at

Are secular humanists obliged to sign up to naturalism? Should we define humanism (or secular humanism, as some prefer to call it in the United States) as involving a commitment to naturalism? Many humanists often define humanism that way, of course.

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