A common view is that we are rational when we weigh the evidence for and against any belief we hold, and if the weight of the evidence says it is more likely than not true we can/should continue to believe it.   If not, then we shouldn’t continue to believe it.   Another approach is to say we should “apportion our beliefs to the evidence.”   These approaches are different from each other, but as far as they go they seem ok and I am not trying to parse them out here.  Instead I want to suggest there is more to having rational beliefs than simply following either of those approaches.

Consider the various Cartesian skeptical scenarios.  These scenarios force us to ask how we know anything about the external world. ( BTW throughout this  blog I am using “know” as imprecise short hand for “reasonably  believe.”  I think “knowing” something does require more certainty that what we “reasonably  believe”  but my sentences are awkward enough so I am sticking with the term “know”)     We might be dreaming.  Some god or evil genius may be manipulating a brain in a vat somewhere causing us to have these experiences etc.  If that was the case it would seem there is still something (a thinking thing) having an experience and so in some sense “I” (this thinking thing) would still exist,  but nothing external to my mind would need to exist as I perceive it.  This is where we get the famous “I think therefore I am.”

Perhaps the easiest way to start getting the idea of these scenarios is the dreaming argument.  Everything I know about the external world is due to my experiences.   However, since I have had dreams where the experiences were such that I couldn’t tell I was dreaming it seems at least possible that I could be dreaming now.   Do I have “evidence” I am not in a very detailed dream?   We can’t step outside of our experience to see what is causing our experiences, so no I do not.  Yet I believe I am not in a detailed dream.  So that would seem to violate the notion that rationality involves “apportioning belief to the evidence.”

Moreover, my rejection of the dreaming argument seems to violate a notion of parsimony.   Every time I have the experience of oncoming headlights traveling opposite my direction on a highway, not only do I have that experience, but I also believe there are physical people with minds and lives of their own in those vehicles. And not only that I think those people will pass headlights and behind those headlights will be real people with real lives and concerns etc.

We do not think there actually are physical things (that may have their own minds) that correspond to the imagery we experience when we dream.  We just think there is the experience of seeing people in our dreams, but those people don’t really exist with minds of their own.   It is possible there are material things existing somewhere that somehow correspond to the dream experiences we have, but our experience does not require that these material things actually exist.   It seems absurd to think any material things exist somewhere corresponding with our experiences – at least when we are talking about “dream experiences.”

But when we talk about experiences we have when we believe we are awake, we somehow think the opposite.   Belief in all those extra material things and minds suddenly seems justified – even though we know from dreams – we could be having the experience without the extra material things or minds existing.

My point is not to try to convince people we should believe we are in a dream or other skeptical scenario – I generally don’t try to convince people of things I do not believe myself.   But rather I want to point out that it is not the “evidence” that is apportioning our beliefs here.  The various skeptical scenarios take up a very small percentage of real estate in my mind.  Most of my beliefs are formed around the notion that I am a real person moving around with other real people with minds of their own.   I do this even though I have no evidence against one of the skeptical scenarios being true.     So in doing that I am certainly not “apportioning my belief to the evidence.”   So if it is rational to believe I am not in a skeptical scenario then there must be more to rationality than “apportioning  belief to the evidence.”

I think there is at least one other reason we do not orient our  beliefs towards a  Cartesian Skeptical scenario.  That is because it is hard or impossible to know what we should do in such a scenario.  The converse is also true.  If we did know exactly what we should do if we were in one of these Skeptical scenarios then it would be a much more rational to orient our beliefs to account for this scenario.  It would be a possibility we could better account for because we would have an understanding of how we should deal with it.   Thus whether we could have some idea what we should do in a scenario is important to whether we should consider it a viable scenario.   But without any understanding of how we should deal with or act in such a scenario, that scenario seems a dead end.   It is only rational to orient our beliefs to viable scenarios not dead end scenarios.

Now let’s get back to reality as we believe it exists.  We see things and believe many of them exist in a material form independent of our experience of them.   But does having this “materiality” actually answer how we should deal with this scenario?   Some would say it does, but I don’t think knowing about how things are tells us how they should be.  So I think just adding materiality to the scenario accomplishes very little if anything.

But regardless of where you stand on that question, you still may agree with me that the viability of a scenario does depend on whether we have any hope of knowing what to do if we are in that scenario.   If we don’t know what scenario we are in then, any scenarios where we would have no clue how to act anyway should be discarded from consideration in orienting our beliefs/actions.   This is because by definition whatever beliefs or actions we orient to would not  be  better or worse than any other in those scenarios.  So a rational person focuses on the possible scenarios where we could know what to do and form their beliefs based on the possibility of those scenarios being true.   Those are the “live options” or what I call the “viable scenarios”.

But do we have to “really” know what to do or can we make up what to do?  That is, do we have to be a “moral realist” or can we be an anti-realist and just admit we are making things up  based on our experiences.    It seems to me that if we can just make up morality through a form of constructivism it wouldn’t matter that we are in a real world as opposed to a skeptical world.   It would seem we could make up morality if we are dreaming or a brain in a vat.   So if the real world we think we live in does not offer anything better than a form of anti-realist morality, then it is no more viable than a Cartesian skeptical scenario.

It seems to me a “viable scenario” requires that 1) moral realism is true and 2) we have a way to know what morality requires.    A scenario where we can’t possibly know what to do in it, is not a viable scenario.  Whether viability is an on off switch, or more of a sliding scale may not be all that clear.  But let’s just say any scenario where 1 and 2 are not met is not a very “lively scenario.”  They would share the same trait that makes the Cartesian doubt scenarios non-viable.

Now consider the possibility that naturalism is true.  We can look at the possibility that naturalism is true without any preconditions and we might say the probability is X.  But then let’s consider the probability that naturalism is true if we are in a scenario where moral realism is true.  Some, myself included, would say that if they knew Moral realism was true then they would think the probability naturalism goes down.  So on moral realism the probability of naturalism becomes X minus Y.    Others might not agree.    But one thing I am fairly certain of, is that if the scenario we are in, includes 1 and 2 then the probability of naturalism being true is very low indeed.

The logic of the arguments made by Sharon Street, Mark Linville and Richard Joyce demonstrate this.   They persuasively argue that if naturalism and evolution is true, even if moral realism is also true, we have no way to reliably know what morality requires.  Street and Joyce believe in naturalism so they reject the idea we can reliably know what moral realism requires even if it is true.   Linnville, and I, think that in light of this sort of argument we should reject naturalism.

For the reasons I stated above I think rejection of naturalism is the more rational option.  That is because holding on to naturalism leads to believing in a non-viable scenario, and rational people orient their beliefs around viable scenarios, naturalism should  be rejected.    If naturalism is a scenario where the probability of 1 and 2 is extremely low, then naturalism implies a scenario that shares the same trait that makes the Cartesian skeptical scenarios non-viable.

Of course, people can dispute whether 1 and 2 are necessary for a viable scenario.  They can also disagree whether 1 and 2 make the probability of naturalism low and vice versa.  But I think this is the best way to understand the structure of my moral argument for God.