Post Debate Reflections (p. 2)
With the following symbolization key:
|M =||Moral oughtness exists.|
|A =||Atheism is true.|
|K =||The relevant background data.|
|Pr(not-M|A&K) =||The probability of M being false given A&K, i.e. the probability of moral oughtness not existing given atheism and the relevant background data.|
Presumably, there are objective probability facts regarding the evidential relationship between data and belief, e.g. “On the basis of the scientific data, quarks probably exist” is objectively true, and this is the sort of probability I have in mind when I say, “Given atheism, moral oughtness probably doesn’t exist” (viz. the objective evidential relationship between “atheism + background data” and “moral oughtness exists”).
My overall argument can summarized thusly, where the Unbiased Atheist is someone who has no intuitions of moral oughtness existing or not existing, including not intuiting propositions that have moral oughtness’s existence implicit in them (e.g. the Unbiased Atheist wouldn’t have the intuition that Something is morally wrong is true or probably true):
|(P1)||If the Unbiased Atheist would be justified in believing Pr(not-M|A&K) is high, then Pr(not-M|A&K) is high.|
|(P2)||The Unbiased Atheist would be justified in believing Pr(not-M|A&K) is high.|
|(C1)||Therefore, Pr(not-M|A&K) is high.|
|(P3)||If Pr(not-M|A&K) is high, then Given atheism, moral oughtness probably doesn't exist is true.|
|(P4)||If Given atheism, moral oughtness probably doesn't exist, then the first premise of the moral argument is probably true.|
|(C2)||Therefore, the first premise of the moral argument is probably true.|
Lines (P1), (P2), and (C1) are more or less the Argument from the Unbiased Atheist (AftUA). The main purpose of the AftUA was to show that on atheism, people’s intuitions of moral oughtness existing are probably delusory and not veridical, which of course implies Pr(not-M|A&K).
(P1) seems true due to what K can and can’t include. K cannot include question-begging propositions like M is true or M is probably false, since then we wouldn’t really be answering the question at hand, which is how likely not-M is in the first place on atheism and not e.g. how likely not-M is given A and M is probably true. SeekSecular balked at the idea of the Unbiased Atheist being a good vantage point for the objective evidential relation between A&K and M, but given which sort of data is admissible for K, what more could one reasonably ask for than someone like the Unbiased Atheist, since any good-vantage-point atheist wouldn’t have the a priori intuition knowledge of moral oughtness existing?
Line (P3) is true by definition, since what I mean by Given atheism, moral oughtness probably doesn't exist just is Pr(not-M|A&K) is high. Line (P4) is supported by a mathematical theorem.
My support for (P2) was the following inductive argument (with each premise predicated with, “If atheism is true, this is true:”), where objective moral oughtness is abbreviated as OMO.
- There is zero empirical evidence for objective moral properties. This supports the idea that the Unbiased Atheist has no good reason to accept M.
- It’d be a remarkable coincidence if moral intuitions happened to line up with what these invisible, causally inert moral properties are really like. Such reliance on remarkable coincidence suggests that we wouldn’t have real knowledge of objective moral truths; at best we’d have coincidentally true beliefs.
- OMO properties are suspiciously queer, akin to invisible and nonphysical gods. To illustrate the general idea behind the Argument from Queerness (AfQ), suppose someone claims there is an invisible unicorn floating above my head. This claim is possible, but not plausible. I would be justified in disbelieving in this unicorn. The unicorn is “queer” enough to be prima facia implausible, and we are prima facia justified in rejecting its existence. Moral oughtness is invisible, nonphysical, empirically detectable, and causally inert. To the Unbiased Atheist, moral oughtness likewise seems “queer,” giving her prima facia justification for disbelieving its existence.
- Evolution occasionally gives false beliefs (e.g. gods). So there’s precedent for evolution giving humans delusory intuitions for invisible nonphysical things. And belief in gods potentially serves some evolutionary purpose: “Don’t do stuff that harms the group even if we’re not watching because the gods are watching and they’ll punish you for doing bad stuff.”
- Moral oughtness beliefs have evolutionary value whether true or not. Suspiciously enough, belief in moral oughtness is kind of like the false belief in gods in potentially serving some evolutionary purpose: to get us to behave in the right ways. Such beliefs have evolutionary value regardless of whether moral oughtness exists.
- Our best theory for why we believe in moral oughtness doesn’t require its existence. Moral oughtness is causally inert; its presence or absence would have no effect on whether we’d get moral intuitions, and so the processes that gave us moral intuitions would do so regardless of whether morality existed. Consequently, we don’t need to posit something so extravagant as these invisible and highly metaphysical moral properties to explain moral beliefs; we can just say it’s a trick of evolution to get us to behave in certain ways.
Note: I am not claiming that any single premise by itself is enough to justify the conclusion, but I do think the combination of all six premises justifies the conclusion.
One of my key claims that the AftUA illustrates is that on atheism the objective evidence suggests that people’s intuitions of M are probably delusory. In some cases our justification for beliefs comes from non-evidential grounds. For example, consider for example the following brain-in-vat (BIV) hypothesis: you are recently created (say, within the past five years) brain in a vat hooked up to a supercomputer feeding you all the memories, sense experiences, and intuitions you know have. We can’t justify our belief that BIV is false based on evidence, because there can’t be any evidence against it. Instead it’s our intuition of its falsity that justifies our belief that BIV is false and that this perceived reality is real. The atheist moral objectivist (AMO) could similarly argue that he’s justified in believing OMO based on non-evidential intuition grounds, even if Pr(not-M|A&K) is high. But a crucial disanalogy is that in the case of BIV we don’t have any objective evidence suggesting BIV is true, whereas on atheism the objective evidence suggests that people’s intuitions of moral oughtness existing are probably delusory. This makes the a priori intuition option much less viable for the atheist.
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 This can be shown with the help of mathematics (given that the sort of “evidence” we have in mind is something that makes a hypothesis more or less likely); see p. 2 of Why evidentialism sucks.
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