I don’t think that “You should two-box in Newcomb’s problem.” is actually a normative statement, even if it contains a “should”: you can rephrase it epistemically as “If you two-box in Newcomb’s problem then you will maximize your expected utility”.
Well, sure, a utilitarian can always “rephrase” should-statements that way; to a utilitarian what “X should Y” means is “Y maximizes X’s expected utility.” That doesn’t make “X should Y” not a normative statement, it just means that utilitarian normative statements are also objective statements about reality.
Conversely, I’m not sure a deontologist would agree that you can rephrase one as the other… that is, a deontologist might coherently (and incorrectly) say “Yes, two-boxing maximizes expected utility, but you still shouldn’t do it.”
I think you are conflating two different types of “should” statements: moral injunctions and decision-theoretical injunctions.
The statement “You should two-box in Newcomb’s problem” is normally interpreted as a decision-theoretical injunction. As such, it can be rephrased epistemically as “If you two-box in Newcomb’s problem then you will maximize your expected utility”.
But you could also interpret the statement “You should two-box in Newcomb’s problem” as the moral injunction “It is morally right for you to two-box in Newcomb’s problem”. Moral injunctions can’t be rephrased epistemically, at least unless you assume a priori that there exist some external moral truths that can’t be further rephrased.
The utilitarianist of your comment is doing that. His actual rephrasing is “If you two-box in Newcomb’s problem then you will maximize the expected universe cumulative utility”. This assumes that:
This universe cumulative utility exists as an external entity
The statement “It is morally right for you to maximize the expected universe cumulative utility” exists as an external moral truth.
Well, sure, a utilitarian can always “rephrase” should-statements that way; to a utilitarian what “X should Y” means is “Y maximizes X’s expected utility.” That doesn’t make “X should Y” not a normative statement, it just means that utilitarian normative statements are also objective statements about reality.
Conversely, I’m not sure a deontologist would agree that you can rephrase one as the other… that is, a deontologist might coherently (and incorrectly) say “Yes, two-boxing maximizes expected utility, but you still shouldn’t do it.”
I think you are conflating two different types of “should” statements: moral injunctions and decision-theoretical injunctions.
The statement “You should two-box in Newcomb’s problem” is normally interpreted as a decision-theoretical injunction. As such, it can be rephrased epistemically as “If you two-box in Newcomb’s problem then you will maximize your expected utility”.
But you could also interpret the statement “You should two-box in Newcomb’s problem” as the moral injunction “It is morally right for you to two-box in Newcomb’s problem”. Moral injunctions can’t be rephrased epistemically, at least unless you assume a priori that there exist some external moral truths that can’t be further rephrased.
The utilitarianist of your comment is doing that. His actual rephrasing is “If you two-box in Newcomb’s problem then you will maximize the expected universe cumulative utility”. This assumes that:
This universe cumulative utility exists as an external entity
The statement “It is morally right for you to maximize the expected universe cumulative utility” exists as an external moral truth.