Russell Blackford is a guest blogger for Sentient Developments.

Over on his Rationally Speaking blog, Massimo Pigliucci has an interesting post on the nature and scope of skeptical inquiry. He is particularly keen to nail down the relationships between scientifically-based skeptical thought, political philosophy, and philosophy of religion (he actually says "atheism", but I think this is a mistake). Pigliucci is a biologist and a philosopher, and these are his three main areas of intellectual interest.

To illustrate his points, Pigliucci introduces a diagram that shows skepticism overlapping with both "atheism" and political philosophy, though they do not overlap with each other. On this diagram, all three fall into a larger realm of critical thinking and rational analysis. Although it's a neat diagram, I think that it (along with the analysis that it illustrates) is somewhat misleading, and in at least one respect even wrong.

On skeptical inquiry

First, however, let's consider something that Pigluicci clearly gets right. He says:

Skeptical inquiry, in the classic sense, pertains to the critical examination of evidential claims of the para- or super-normal. This means not just ghosts, telepathy, clairvoyance, UFOs and the like, but also — for instance — the creationist idea that the world is 6,000 years old. All these claims are, at least in principle, amenable to scientific inquiry because they refer to things that we can observe, measure and perhaps even repeat experimentally. Notice, of course, that (some) religious claims do therefore fall squarely within the domain of scientific skepticism. Also in this area we find pseudohistorical claims, such as Holocaust denial, and pseudoscientific ones like fear of vaccines and denial of global warming. Which means of course that some politically charged issues — like the latter two — can also pertain properly to skeptical inquiry.

I'm with him completely on this. Claims about ghosts, the age of the Earth, and pseudohistorical or pseudoscientific theories, are all within the ambit of skeptical inquiry as so defined. Skeptical inquiry in the sense under discussion is not about taking positions that are in the minority. It is about rational inquiry into various claims, popular or otherwise, using the means available not only to science but also to such fields as history. Accordingly, when someone claims to be a "climate change skeptic" she is using words in a different sense.

It is always possible, of course, that a view with widespread, or even consensus, support from current science is nonetheless incorrect. Still, skepticism in the sense that Pigliucci is discussing is not about challenging the majority position. It is about rational investigation, especially of extraordinary claims - extraordinary in the sense that they fit badly, or not at all, with the best picture of the world built up through science, scholarship, and ordinary observation.

In particular, we are not talking here about some kind of radical epistemological skepticism, such as Descartes wrestled with and sought (unsuccessfully) to transcend or escape. Nor are we talking about skepticism as regards the status quo of scientific and scholarly knowledge. That sort of skepticism is possible, of course, and it may sometimes be justified. However, it is not legitimate to act as a skeptic merely in this sense, while attempting to get approbation for being engaged in skeptical inquiry in the different, and quite familiar, sense that Pigliucci describes.

Accordingly, I think that Pigliucci is correct when he later denounces the practice of "using the venerable mantle of skepticism to engage in silly notions like denying global warming or the efficacy of vaccines." As he says, "That’s an insult to critical analysis, which is the one thing we all truly cherish."

Pigliucci is also quite correct to show an overlap between atheism and skeptical inquiry, although atheism is a substantive position, not a field of inquiry, so he should really have written "philosophy of religion". He is correct that what philosophers of religion do when they investigate religious claims, such as those about the existence of various gods, overlaps with scientific skepticism or skeptical inquiry. I think, however, that he unnecessarily deprecates the extent of this overlap. This I'll return to.

On political philosophy

As for political philosophy, Pigliucci sees this too as overlapping with skeptical inquiry. After all, he says, some skeptical inquiry (e.g. into the claims of holocaust denialists) has implications for political philosophy.

This seems to be correct. However, he doesn't seem to have noticed that philosophy of religion may also have implications for political philosophy, and vice versa. For example, some religious positions, if correct, have definite implications for the role of the state. After all, various comprehensive worldviews based on religion claim that the state should enforce religious systems of morality or law; these worldviews are starkly opposed to liberalism and pluralism.

Less obviously, it is at least conceivable that a political position on an issue such as social justice could have implications for whether we should accept certain religious positions. We might develop a politically-based theory of justice, then ask, "Does the world seem to have been created by a just God?" Surely the answer could feed back into at least some views about the existence or nature of God. In any event, the diagram seems to be wrong, not just misleadingly presented, when it shows no overlap between political philosophy and "atheism".

Science and philosophy

While this may be the only error, strictly speaking, there are other problems with the analysis. They emerge when Pigliucci tries to defend the view that atheism is a philosophical position, rather than a scientific one. There is a sense in which this is clearly, but rather trivially, true. The issue of God's existence is, after all, examined by philosophers of religion, and not usually by biologists or physicists, and the pedagogical and other decisions that have led to this have not been merely arbitrary. But there's also a sense in which Pigliucci's account is misleading. Here's how he attempts to persuade us:

Now, I have argued of course that any intelligent philosopher ought to allow her ideas to be informed by science, but philosophical inquiry is broader than science because it includes non-evidence based approaches, such as logic or more broadly reason-based arguments. This is both the strength and the weakness of philosophy when compared to science: it is both broader and yet of course less prone to incremental discovery and precise answers. When someone, therefore, wants to make a scientific argument in favor of atheism — like Dawkins and Jerry Coyne seem to do — he is stepping outside of the epistemological boundaries of science, thereby doing a disservice both to science and to intellectual inquiry. Consider again the example of a creationist who maintains in the face of evidence that the universe really is 6,000 years old, and that it only looks older because god arranged things in a way to test our faith. There is absolutely no empirical evidence that could contradict that sort of statement, but a philosopher can easily point out why it is unreasonable, and that furthermore it creates very serious theological quandaries.

The difficulty here should be obvious. Scientist do use logic and "more broadly reason-based arguments"; they do so all the time. Much of science proceeds by processes that include logical deduction, and there are no a priori boundaries to the kinds of "broadly reason-based arguments" that scientists can use.

Let me qualify that: there may be some claims that should be conceded as lying outside of science. These may be more a matter of the historical construction of science as a set of institutions than anything else, but I'll not press that issue. Instead, let's agree, for the sake of argument, that scientific reasoning alone cannot give us correct values or correct moral norms. Let's also assume that such things as correct values and moral norms actually exist - though there's much to be said here - but that science alone cannot provide them.

It's also strongly arguable that science is unable to deliver correct statements about fundamental epistemological principles. Take, for example, a principle such as, "All truths except this one are truths that are known through science." A claim like that, whatever its other features, does not seem to be known through science. Nor does its negation seem to be known through science. I'll assume, then, that some meaningful and rational discussion of epistemological issues lies beyond the boundaries of science.

Still, this is not the sort of example that Pigliucci offers. Instead, he begins with the claim that the universe is really 6,000 years old. Science has, of course, produced plenty of evidence that this is just false, that the universe is more like 13 to 14 billion years old. Our own planet is roughly 4 to 5 billion years old. All of this surely counts against the claim that the universe is really only 6,000 years old. Pigliucci is quite correct to see this as an example of science falsifying a religious claim, and I suspect he'd think there are many such examples. Furthermore, he doesn't try to assert, in the fashion of Stephen Jay Gould, that there are some kinds of claims that it is illegitimate for religion to make. Thus, quite correctly in my view, he does not accept the principle of Non-Overlapping Magisteria.

However, what if somebody replies that God arranged for the Earth to look far older than it really is, in order to test our faith? Here, Pigliucci thinks that science (and hence skeptical inquiry) reaches a limit. He claims, in effect, that philosophers have a reply, whereas scientists must stand mute.

I disagree with this. The scientist is quite entitled to reject the claim, not because it makes falsified predictions or conflicts directly with observations (it doesn't) but because it is ad hoc. It is perfectly legitimate for scientists working in the relevant fields to make the judgment that a particular hypothesis is not worth pursuing, and should be treated as false, because it has been introduced merely to avoid falsification of a position that is contrary to the evidence.

Scientists might take some interest in claims about a pre-aged Earth if they were framed in such a way as to make novel and testable predictions, but as long as all such claims are presented as mere ad hoc manoeuvres to avoid falsification of the claim that the universe is really 6,000 years old, a scientist is quite entitled to reject it. A philosopher should reject it for exactly the same reason. Philosophers don't have any advantage over scientists at this point.

Thus, Pigliucci is unnecessarily limiting the kinds of arguments that are available to scientists. He writes as if they are incapable of using arguments grounded in commonsense reasoning, such as arguments that propose we reject ad hoc thesis-saving hypotheses.

That's not to say that the resources of science never run out. But when they do it is often for merely practical reasons. For example, it may be because of because a problem that confronts us requires that we consider points that scientists are, in practice, not well-trained to consider. If that's the problem, it's a matter of pragmatic division of labour, not of an epistemological resource that's out of bounds to scientists in principle.

Accordingly, we might have good reason to say that scientists, as a class, are not that well-trained to solve puzzles that arise within philosophy of religion. But it doesn't follow that any specific scientist - Richard Dawkins, say - is poorly equipped to do so by his training and study. Nor does it follow that whatever arguments Dawkins uses are "not scientific". They may be shared with philosophers, but it by no means follows that they are out of bounds for use by scientists. They may not be distinctively scientific, but that's another matter.

Moreover, it is possible that certain arguments that are legitimately open to scientists to develop might turn out to be decisive, one way or another, with respect to issues in philosophy of religion. Pigliucci says: "When someone, therefore, wants to make a scientific argument in favor of atheism — like Dawkins and Jerry Coyne seem to do — he is stepping outside of the epistemological boundaries of science, thereby doing a disservice both to science and to intellectual inquiry." But we can't know that in advance. It's certainly not a truism which we're compelled to accept.

Two examples

It might help to consider some contrasting examples. First, suppose that a cryptozoologist claims that a gigantic, previously undiscovered species of ape lives in the forests of New England (I'm thinking of the location in North America, not the identically-named location in Australia, or any other place with the same name). I assume that it would be pretty straightforward to work out what would be good evidence for or against the existence of this new species - what kinds of observations we would need to make to confirm its existence directly, what kinds of observations would pretty much preclude its existence, and what observations would be inconclusive. It wouldn't be too hard, at least in principle, to get together a group of zoologists, ecologists, and the like, to investigate the matter. Thus, no one doubts that the existence or otherwise of this spectacular New World primate is a scientific question.

What, however, if the claim is made that a Jewish apocalyptic prophet performed miracles during the first century of the Common Era? This looks like a job for historians - thus we immediately assign it to folks in the Faculty of Arts, rather than the Faculty of Science. The historians are likely to ask for historical evidence of the existence of this prophet and of his alleged miracles. Surely that's reasonable? This may involve (among other things) investigating various documents that supposedly record the prophet's acts, including the miraculous ones. How should the historians proceed?

Well, it will be a bit complicated, though perhaps no more so than the job of the scientists looking for the giant ape.

The historians might wish to establish, using a variety of means available to them, whether the documents were contemporary with the events described. They might examine the documents to try to determine whether they were originally created in their current form, or whether some parts are older, and perhaps more reliable than others. They might attempt to determine whether any of the events recorded in the documents are of such a nature that, if they really happened, they would have been recorded in secular texts of the time. For example, the documents might claim that on such and such a day five hundred long-dead corpses rose from a major cemetery and wandered the streets of Rome, accosting sinners and soldiers. Historians can check whether any of the secular historical texts and other unbiased records describe such an event.

They might also check carefully to see whether the documents are internally consistent and consistent with each other, and the nature of the inconsistencies if any are found. They might take into account whatever is known about the propensity for the lives of prophets to be mythologised, in the sense that the truth is embroidered with (false) accounts of miracle working. They might look to forensic psychologists, among others, for knowledge of when and how people come to believe things (and even to believe they saw things) that turn out to be false.

Many of the skills needed to do all this (including language skills) are taught in arts faculties rather than science faculties. And yet, there is nothing in the kinds of investigations that the historians will be involved in, or the kinds of arguments that they will use in attempting to settle the issue, that is conceptually remote from scientific reasoning. The same sort of logic will be employed; ad hoc hypotheses will be rejected; facts will be weighed.

It's true, of course, that the job will be assigned to people who are well trained in interpreting the nuances of language and the effects of culture, rather than in (for example) mathematics and the conduct of experiments. On the other hand, some scientific apparatus might be used, such as computers programmed to analyse texts to help determine whether they were written by the same person. Hypothetico-deductive reasoning might be relied on at various points. Most importantly, none of the techniques that I am describing are totally unavailable to scientists - it's more a question of emphasis in training. It makes sense to call the investigation a "scientific" one, even though conducted by people employed within arts faculties.

Or we might say that it's an issue for historians, not scientists, while adding that there is no radical difference between the epistemological resources of history and science. It's just that different emphases in training and skill mixes tend to be needed, for everyday purposes, by scientists and historians. If someone had all these skills, they would complement each other and mesh together just fine. When we talk about the methods of scientists and compare those of historians, there are no radically different "ways of knowing" involved. Moreover, there is no reason in a case like this why the historical evidence and arguments should be considered anything less than decisive.

What about philosophers?

Imagine that a philosopher seeks to investigate whether a divine being created the Earth. In that case, she might be faced with evidence of many kinds. For example, one item of alleged evidence, among the many, might be the claim that a Jewish apocalyptic prophet who performed miracles in the first century of the Common Era claimed to be the son of this being. The philosopher might conclude that the alleged testimony of the apocalyptic prophet would carry weight if: (1) he really existed and said what is recorded, and; (2) he really did perform the alleged miracles.

In checking into this evidential issue, the philosopher is likely to ask for help from historians, at least in the first instance, rather than from scientists, thus keeping the investigation within the Faculty of Arts. But, let's remember, the historians will not be using techniques or arguments that are radically foreign to science and scientists - they have a different skill mix but not a radically different way of knowing.

What if the apocalyptic prophet were alleged to have made various claims that are in conflict with current science, e.g. that the Sun is a ball of white hot metal circling the Earth? A philosopher might take this as evidence (perhaps not strong evidence, but still ...) that the prophet was all too human and not, in fact, the child of a divine being. Note, however, that she would depend on scientists to tell her that the claim is, in fact, incorrect, and on historians to tell her whether it is likely that the prophet really said what is attributed to him. At no stage in this inquiry - at least no stage discussed so far - does the philosopher do anything that's radically foreign to the scientific reasoning.

In the upshot, the question about a divine being who created the Earth is likely to involve input from many disciplines, with people who have many different skill sets providing relevant data and sub-conclusions. The beleaguered philosopher must sort out highly complex arguments using all this material, while (probably) not having the skills herself to undertake the textual analysis performed by the historian, or the physical experiments that were performed by scientists in the past when they discovered the true nature of the Sun. But she has not yet used arguments or evidence that are beyond those available, in principle, to scientists. It's simply a matter of division of labour within academic institutions and the availability of people with different skill sets.

Accordingly, a question about the existence of a divine creator is different, in a practical way, from a question about an unknown species of gigantic ape in New England. Whereas the latter can be assigned to scientists from a small group of relevantly related disciplines, the latter may call on data and conclusions from many disciplines, across faculty boundaries, and involving many different skill sets. The overall argument may be extremely complicated in the sense that there are many sub-arguments (from many disciplines) feeding into it. Accordingly, this kind of argument gets assigned to philosophy, the repository for arguments that involve many considerations (and sub-conclusions) from many fields.

But, while that is a reason to say that a question such as this is philosophical, it still does not follow that any of the reasoning done is unavailable to scientists who are broadly enough trained. It is simply that some of the skills depended on at different points in the overall argument come from people with training that scientists don't usually have - e.g. advanced knowledge of ancient languages.

Not only that, but some of the sub-conclusions derivable from science might turn out to be decisive. If we're told enough about the God concerned, we might be able to deduce that it doesn't exist (or that it does) purely on the basis of data and arguments that are available to scientists, without even calling in the historians to help establish what took place in the Middle East 2000 years ago. Thus, Pigliucci is wrong when he suggest that atheism cannot, as a matter of principle, be established by scientific arguments. Whether or not it can be, in respect of one god or another, remains to be seen.

For example, consider the claim that an all-benevolent, all-powerful, all-knowing God exists, and has existed from eternity. It is well within the skills of scientists to give this consideration, deduce what kinds of events would contradict the claim, and look for evidence of such events - e.g. evidence of nature red in tooth and claw, the existence of horrible pain experienced by sentient creatures, and that much of this has nothing to do with any exercise of free will by human beings.

Although there is no science that is specifically charged with investigating the existence of such a deity, there easily could be an interdisciplinary effort by various scientists, particularly including biologists, that justifiably concludes that a god of this kind does not exist. If a theist who supports the existence of a god of this kind resorts to ad hoc manoeuvres, the scientists will be well equipped to recognise them as such.

None of this is to deny that some of what goes on in philosophy is different from what goes on in any scientific discipline. But it is not known in advance that any of these things will be required to settle, decisively, the truth of a particular religious claim.

Perhaps, however, there could be religious claims that it is possible to settle only if we first settle issues of morality or fundamental epistemology that lie outside of science. Accordingly, there is a possibility that some claims about the existence of a god will require sub-conclusions that seem to lie beyond the scope of science. Thus, we can't guarantee that all questions about the existence of a God or gods are decisively resolvable by science, or by methods (such as those of historical-textual scholars) that are allied with it.

Conclusion

We should come to a weaker conclusion than Pigliucci's. Pace Pigliucci, it is not wrong in principle to put scientific arguments for atheism (or for theism). It cannot be ruled out in advance that the kinds of arguments used by scientists will be decisive.

Even if the scientific arguments are not decisive by themselves, they may be when taken in conjunction with other considerations. In that case, they may still be of crucial importance in reaching an atheistic (or, indeed, theistic) conclusion and in that case it appears unfair to criticise somebody like Richard Dawkins for overstepping the bounds.

After all, philosophers are forced to draw upon resources from other disciplines. Why can't a biologist do likewise, obtaining important data and sub-conclusions from his own field, while also relying on input from (say) historians and philosophers for the full argument? If we accept that picture, scientists in the relevant field(s) do have an advantage over people with no scientific training. The advantage will consist in a the possession of both a useful knowledge base and the skills in developing relevant kinds of arguments. While the ultimate conclusion may turn out to require assistance from, say, historians or philosophers, that does not render scientific qualifications irrelevant.

In any event, Pigliucci is surely correct about one thing: the questions relating to theism, atheism, and philosophy of religion in general, should be investigated rationally. Philosophers, historians, and various kinds of scientists may all have a role to play in that investigation (though it is still possible that one or other set of arguments by itself will be decisive). There is no "way of knowing", lying somewhere beyond the realm of rational inquiry, that can solve the problem for us. We are left with our reason and intelligence, and the ongoing advance of knowledge.

But possessing those is no small thing. It's something we must always celebrate, the only key to a (post)human future on or beyond our blue-green Earth.

Russell Blackford's home blog is Metamagician and the Hellfire Club. He is editor-in-chief of The Journal of Evolution and Technology and co-editor, with Udo Schuklenk, of 50 Voices of Disbelief: Why We Are Atheists (Wiley-Blackwell, 2009).