Post Debate Reflections (p. 3)
Recall that (P1) is, “If the Unbiased Atheist would be justified in believing Pr(not-M|A&K) is high, then Pr(not-M|A&K) is high,” the idea being that the Unbiased Atheist is a good vantage point from which to evaluate the objective evidential relation between not-M and A&K. What we might call the main objection is the idea that premise (P1) is false, on the grounds that the Unbiased Atheist would not be a good vantage point for evaluating Pr(not-M|A&K). It’s an interesting objection and not one I expected (I instead expected (P2) would be the target of choice). But how to go about making this objection precisely?
One way would be to argue that M should be part of K, and if one does that Pr(not-M|A&K) would be as low as Pr(not-M|A&M). But this tactic seems philosophically inappropriate and question begging. To illustrate why, suppose an atheist proposes a probabilistic argument from evil, arguing that Pr(not-God|Evil&K) is high where K is some appropriate background knowledge (including e.g. free will for the theist who attempts a free will theodicy). Suppose I argue that since belief that God exists is a rational intuition, we should include it in K, and when we do we effectively get Pr(not-God|Evil&God) which of course is extremely low, and thus Pr(not-God|Evil&K) is low. Therefore, I argue, the probabilistic argument from evil fails.
Even though I think the intuition that God exists is a rational intuition, this maneuver does not seem philosophically appropriate. The intuition of God’s existence, while perhaps rational, is a subjectively experienced intuition, and the objective evidence would still be strongly against theism if Pr(not-M|Evil&K) were high when propositions like God exists are excluded from K. Similarly, it seems philosophically inappropriate and question begging to just include morality’s existence (or some other proposition that has morality’s existence implicit in it) in K to argue that my “probabilistic argument from atheism” against moral objectivism doesn’t work.
A different approach would be, although not including a proposition like Morality exists in K, the intuition gives us nonpropositional support for morality’s existence, i.e. actually experiencing the intuition justifies our belief more than the mere fact that People have the intuition that morality exists. This a priori moral intuition makes us inclined to believe in morality, and this intuition needs to, for lack of a better term, bias our evaluation Pr(not-M|A&K) compared to a more neutral vantage point.
The problem is while that while a priori subjectively experienced intuitions about whether a theory is true might be appropriate for subjective probability assessments, the type of probability the argument is using is the objective evidential relation between the belief (moral objectivism) and the data (A&K). To illustrate, suppose that prior to examining the relevant scientific data, Smith has an overpowering intuition that creationism is true, and Jones has an overpowering intuition that evolution is true. Smith and Jones might come away with different subjective probability assessments of how likely evolution is after examining the scientific data, but to correctly evaluate the objective evidential relation between data and theory a more neutral vantage point seems appropriate. Hence the Unbiased Atheist.
In response, one could say that when a person’s intuition is a rational one, that person should use the intuition when evaluating the probability of a theory given the data if she is to assess the overall rationality of the belief. The problem is that even a rational subjectively experienced intuition is still subjectively experienced, and the type of probability the argument is using is nothing more than the objective evidential relation between theory and data, and not the overall rationality of a person’s belief.
To illustrate the difference between the two, suppose Smith and Jones know that in a particular factory 2% of all widgets shaped like a cube contain metal. Let T represent The widget from the factory contains metal and let D be The widget from the factory is shaped like a cube. The objective evidential relation between T and D is such that Pr(T|D) = 0.02, and Pr(not-T|D) = 0.98. Smith is a cyborg who knows she has a metal-detecting implant that gives her the intuition that a widget contains metal whenever a metal-containing widget is in her hand. Unbeknownst to Jones, Smith’s intuition tells her the cube-shaped widget contains metal and she is rational to believe it contains metal, but this does not change the objective evidential relation between T and D, which is still Pr(T|D) = 0.02, since Pr(T|D) represents the probability of the widget containing metal given just the shape of the widget. The overall rationality of a Smith’s belief is such that she is rational in thinking the widget contains metal despite Pr(not-T|D) being high.
In some cases it is possible for rational intuition to be relevant in evaluating the objective evidential relation between data and theory, e.g. intuiting principles of inductive inference. But the a priori intuition that moral oughtness is associated with certain natural properties is no more a rule of inductive inference than the a priori intuition that God’s existence is currently associated with the universe’s existence. The subjectively experienced intuition of morality’s existence, while perhaps a rational intuition, does not seem like it should affect our evaluation of Pr(not-M|A&K) when it’s the objective evidential relation between not-M and A&K that we’re trying to determine, and not the overall rationality of the belief.
A more promising approach is to bite the bullet and say that Pr(not-M|A&K) is high but only in the sense of an objective evidential relationship between not-M and A&K, and not the overall rationality of the belief. Consider the case of cyborg Smith. Although Pr(not-T|D) is high in the objective evidential relation sense, cyborg Smith’s intuition nonetheless makes it rational for her to believe the widget probably contains metal. Similarly, even though Pr(not-M|A&K) is high in the objective evidential relation sense, moral intuition still justifies an atheist’s belief that objective morality probably exists. Pr(not-M|A&K) as an objective evidential relation between theory and data ultimately becomes irrelevant, and the atheist moral objectivist is still justified in rejecting the moral argument’s first premise.
The problem comes when A&K encompass all the relevant data, including the existence of moral intuition, and when this objective evidence suggests that the moral intuition is likely delusory. To illustrate, let’s modify the cyborg Smith scenario as follows: Jones shows Smith objective evidence suggesting that Smith’s metal-detecting implant would give Smith the intuition that the widget contains metal even if the widget did not contain metal, making Pr(not-T|D&K) high. Cyborg Smith’s intuition would no longer provide adequate justification, and Pr(not-T|D&K) being high gives her strong rational grounds to believe the widget does not contain metal. Similarly, on atheism the objective evidence suggests we would have the moral intuition even if morality did not exist. Moral oughtness is causally inert; its presence or absence would have no effect on what intuitions our brains would give us, nor would it have any effect on the evolutionary and environmental processes that gave us our brains. On atheism, this would seem to undercut our moral intuition as a source of adequate justification, and Pr(not-M|A&K) being high does seem to strongly justify the moral argument’s first premise.
All things considered, I see no good way for the atheist to avoid the intellectual force of my argument for the moral argument’s first premise, but I appreciate my opponent’s attempt to knock it down.
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 For the record, I do not believe that Pr(not-God|Evil&K) is high, but the hypothetical scenario of it being high does serve as a useful illustration.
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