In the thread to my article “In defense of existential arguments for belief in God” Matt DeStefano commented that my argument
“doesn’t address what Jerry (or Harris) is pushing in this dialogue. Either God exists, or God doesn’t exist. No amount of “wishing” (or positive benefits associated with belief) justify accepting the proposition that “God exists”. With what you’ve said here, the man who believes in the giant diamond in his backyard is justified based on the (alleged) positive effects on his life.”
Unfortunately Sam Harris’ diamond illustration demonstrated one thing: he didn’t really understand the argument. So I responded to Matt by summarizing the existential argument succintly:
If you have reason to believe that believing p will contribute to a happier life and believing not-p will contribute to a miserable life, and the evidence for p and not-p is, in your assessment, roughly approximate, and there is no other mitigating benefit for believing not-p over believing p, then you have a prudential ground to believe p over not-p.
That’s the core of the argument. Note that the argument does not suggest (as Harris errantly assumes) that the conclusion makes p more likely to be true than not-p. Rather, it simply establishes that prudential considerations can make it more reasonable to accept p than not-p.
Of course you might ask: But what about agnosticism? What if being agnostic could also secure the existential benefits of belief in p while also recognizing the lack of sufficient evidence for p and not-p? Wouldn’t that make agnosticism better in this situation?
If that were all true then yes, it would. However, it wouldn’t if the subject contemplating his existential situation believed that accepting agnosticism about p and not-p would have a cumulative negative impact on his life roughly commensurate to belief in not-p. This is how I put it in the comment:
“(I could make this more complicated and precise by also noting that withholding belief in both p and not-p [i.e. agnosticism] would have a negative existential benefit comparable to belief in not-p leading to the only epistemic attitude conducive to over-all human flourishing being assent to p.)”
So all in all this seems to provide an appreciable defense for those who, on rational grounds, accept p (God exists) because they cannot bear either the thought of atheism (God doesn’t exist) or agnosticism (I don’t know whether God exists or not).
But then what about Harris’ diamond? One could interpret Harris’ diamond illustration as a sort of reductio ad absurdum for the argument I provided. Consider:
If Jones has reason to believe that believing there is a big diamond in his backyard will contribute to a happier life and believing there is not a big diamond in his backyard will contribute to a miserable life, and the evidence for the big diamond being in his backyard and the big diamond not being in his backyard is, in his assessment, roughly approximate, and there is no other mitigating benefit for believing the big diamond is not in his backyard over believing it is in his backyard, then Jones has a prudential ground to believe the big diamond is in his backyard over believing it isn’t.
Are we obliged to accept this conclusion?
I have two responses to this question. But first a sidebar observation: while Harris is supposed to be a philosopher of some note (at least in the public imagination) he rarely if ever displays analytic rigor in his analysis. Illustrations like the big diamond, while played to great rhetorical effect in front of a self-satisfied secular audience, do little to illumine the real issues.
Now to the response.
There are two significant problems with this extension of the argument. The first is that we have excellent reason to believe that Jones would be wrong and that believing there is a large diamond in his backyard would ultimately be destructive of the cumulative happiness of his life. Granted it may yield short-term benefits of familial bonding as all dig in the backyard. But those short-term benefits are akin to a drug high, and would soon be followed by a painful withdrawal. By contrast, we have good reason to believe that those who opt to be theists on prudential grounds would in fact find the payoff of their investment of a happier life. There are millions of people like Bilbo who can attest to this fact. By contrast, the diamond digging neighbor who has a happier life for that belief exists only in Sam Harris’ overactive imagination.
Second, highly intelligent, reasonable people (e.g. professional philosophers of religion) can assess the evidence for God’s existence and come to the conclusion that neither “God exists” nor “God does not exist” is adequately evidenced to compel belief simply based on that evidence. In other words, these experts could conclude that God plausibly exists without finding the evidence for that proposition adequate to warrant it. At this point prudential considerations for belief enter the discussion.
By contrast, Harris has no highly intelligent, reasonable people who would believe that a giant diamond could plausibly be in the man’s backyard. Consequently, that illustration lacks the minimal evidential base to make prudential considerations a viable part of the conversation.