What is philosophical consistency?

Jerry Coyne responded to Massimo Pigliucci's characterisation of Coyne's view philosophical consistency as naive thus:

What I mean by “philosophical consistency” is that one’s philosophies are consistent. In the case of a scientist, one’s scientific philosophy is that you don’t accept the existence of things for which there is no evidence. In the case of a religious person, your philosophy requires you to believe in things for which there is either no evidence or counterevidence. It’s just that simple.

John Pieret counters:

To start with, as I have pointed out before, if, in fact, science is "a philosophy" or a "worldview" (i.e. a metaphysical belief about how best to approach all aspects of life), then it is on equal footing with religion under the American Constitution. If, as Coyne correctly points out, science contradicts at least some religious claims, then science cannot be taught as true in American public schools but, at best, can be taught in comparative religion or philosophy classes as one competing "worldview" out of many.

If, on the other hand, it is not a weltanschauung, there is nothing "inconsistent" in applying the scientific method to some things and not to others, depending on your objectives.

John Pieret argument seems to be that if Coyne is right, and a scientist must be philosophically consistent in the sense that Coyne argues for, then science is another religious belief or worldview. I'm not from the U.S. and I'm not involved in the battle to keep creationism out of state schools here in Australia. Partly because we have no separation of church and state, and partly because religious folks get lots of government funding, pork-barrelling each election, to run their own schools and teach whatever they like, sadly. I'll leave that issue to the side.

Setting aside the term philosophical, what is consistency?

I understand consistency to mean that a particular set of beliefs do not contradict a subset of the same beliefs. This is internal consistency. They need not be externally consistent, that is, the beliefs might concern the behaviour of dragons, and be consistent, even though external to the person, there are no dragons. I think it's too much to ask that any human be internally consistent in all their beliefs, let alone externally consistent. We're all a bit irrational, and perhaps this is just to be expected with a jerry-rigged brain bestowed by evolution. I think what I've described is logical consistency. Douglas Walton*, a philosophy professor, who holds a doctorate in philosophy - Doctorates appear to be important if you read the comments below some of the links. Massimo Pigliucci has 3 apparently, Russell Blackford has 2, Jerry Coyne has at least 1, I have none, sniff. - declares that

[t]wo statements are inconsistent if it's not logically possible for both of them to be true.

That is, for two statements to be consistent, the can logically be true, they don't contradict. Coyne defines philosophical consistency as the situation in which

one’s philosophies are consistent.

Do this mean that science, and religion, are philosophies? If so, and if they are consistent, then they do not contain specific (or intertwined groups of) beliefs that contradict one another. When I read the term philosophical I think it relates to such thing that generally are part of philosophy, such as epistemology (knowledge), ethics, metaphysics, etc. It seems here that Coyne is using philosophical in the sense that someone might say Buddhism is a philosophy, or my philosophy is an eye-for-an-eye. If that's the case, then we are talking worldviews.

Maybe Pieret's points about separation of church and state are correct then, but I don't think that matters here because whether we like the consequences or no of an argument has no bearing on the truth of that argument. I think then we can say that if certain scientific beliefs are true, the it is logically inconsistent that other beliefs posited by religion. In this sense (science is a worldview) then a scientist qua scientist must hold the scientific worldview and thus couldn't hold to any religious beliefs that were contradicted by science on pain of being inconsistent. Maybe Pieret has a point here. (As a gnu atheist, that hurt to write.**)

Coyne continues by saying that

[f]urther inconsistency comes from the fact that science and faith find out things in different ways: scientific knowledge is attained through observation, experimentation, and agreement among practitioners. “Religious knowledge” (and I put it in quotes because it’s an oxymoron) comes from dogma, authority, and personal revelation. This leads to the final inconsistency: the stuff that religion “finds out” contradicts what science finds out.

I think Coyne is on firmer ground here. But this is a different type of inconsistency. It's a methodological consistency. What method, or spectra of methods does one use to gain knowledge in the world? Rational methods such as science, but including mathematics, philosophy, critical thinking, logic, etc, or revelation, spiritual insight, and scripture? This doesn't seem to be touched by Pieret's criticism.

As an aside, I think the objection that Coyne and other gnu atheists are scientistic is false, if only because all seem to have said more than once that they don't hold science alone as reliable ways of gaining knowledge. I take them at their word. Also, the sort of response that you don't use a method to know that someone loves you (hates you, etc) is a weird one. You won't use science, as it's understood, as a methodology, but if you don't use critical thinking or some variety of rationality, how can you tell if your infatuation (not arrived at rationally) isn't returned and you're in danger of stalking? This seems to parallel the distinction between context of discovery and context of justification that occurs in science and Massimo Pigliucci thinks counts against Jerry Coyne, though I don't see how. Anyway, I just put in this aside as I've seen these kinds of objections before.

So, we have science, and other rational methods of gaining knowledge. The thesis of epistemic incompatibility that Jerry Coyne and others have asserted, that science as a method of gaining knowledge, is incompatible with, religion is firmer ground from which to launch arguments.

Is the epistemic incompatibility of science and religion or lack thereof inconsistent in the sense that Douglas Walton argues? Is it logically impossible that science arrives at a truth that has been arrived at (I'm being generous here) via religious methodologies? Obviously not. A prophet might just pluck an idea out of his nether end, tell it to his followers and it becomes part of that religions beliefs. It could be that this idea is in fact serendipitously true, and science, in its own time, arrives at this truth. Not a big deal I'd have thought. What is interesting is that lots of putative knowledge claims given by religion have been shown to be wrong. They could have been right as Russell Blackford (sorry, no quote) has pointed out, but weren't. As an epistemic method religion, to put it politely, is not so good and it's tools are incompatible (but not inconsistent in the Walton sense) with science and other rational methods.

I hope I haven't misrepresented the arguments of any of the gentlemen I've quoted above. If I have, please correct me. If you feel that I've botched the whole thing, or just part of it, let me know. I appreciate learning how I went wrong even more than just the knowledge that I went wrong. I'm sure I did go wrong somewhere. Wrong linkage, poor spelling, poor grammar and crimes against readability are a given.

*Walton D. Fundamentals of critical argumentation.

** Various attempts at humour or self-deprecation appear in this post. I could have used smileys, but then the whole thing would've been even worse on the eye ;).