A detail: I find the “much harder” in the following unnecessarily strong, or maybe also simply the ‘moral claim’ yes/no too binary (all emphasizes added):
If the rich generally do not have a moral claim to their riches, then the only justification needed to redistribute is a good affirmative reason to do so: perhaps that the total welfare of society would improve [..]
If one believes that they generally do have moral claim, then redistributive taxation becomes much harder to justify: we need to argue either that there is a sufficiently strong affirmative reason to redistribute that what amounts to theft is nevertheless acceptable, or that taxation is not in fact theft under certain circumstances.
What we want to call ‘harder’ or ‘much harder’ is of course a matter of taste, but to the degree that it reads like meaning ‘it becomes (very) hard’, I’d say instead:
It appears to be rather intuitive to agree to some degree of redistributive taxation even if one assumed the rich had mostly worked hard for their wealth and therefore supposedly had some ‘moral claim’ to it.
For example, looking at classical public finance 101, I see textbooks & teachers (some definitely not so much on the ‘left’) readily explaining their students (definitely not systematically full utilitarians) why concave utility means we’d want to tax the rich, without even hinting at the rich not ‘deserving’ their incomes, and the overwhelming majority of student rather intuitively agreeing with the mechanism, as it seems to me from observation.
I think the OP uses the word “justify” in the classical sense, which has to do with the idea of something being “just” (in a mostly natural-rights-kind-of-way) rather than merely socially desirable. The distinction has definitely been blurred over time, but in order to get a sense of what is meant by it, consider how most people would find it “very hard to justify” sending someone to prison before they actually commit (or attempt to commit) a crime, even if we could predict with arbitrarily high certainty that they will do so in the near future. Some people still feel this way about (at least some varieties of) taxation.
That could help explain the wording. Though the way the tax topic is addressed here I have the impression—or maybe hope—the discussion is intended to be more practical in the end.
A detail: I find the “much harder” in the following unnecessarily strong, or maybe also simply the ‘moral claim’ yes/no too binary (all emphasizes added):
What we want to call ‘harder’ or ‘much harder’ is of course a matter of taste, but to the degree that it reads like meaning ‘it becomes (very) hard’, I’d say instead:
It appears to be rather intuitive to agree to some degree of redistributive taxation even if one assumed the rich had mostly worked hard for their wealth and therefore supposedly had some ‘moral claim’ to it.
For example, looking at classical public finance 101, I see textbooks & teachers (some definitely not so much on the ‘left’) readily explaining their students (definitely not systematically full utilitarians) why concave utility means we’d want to tax the rich, without even hinting at the rich not ‘deserving’ their incomes, and the overwhelming majority of student rather intuitively agreeing with the mechanism, as it seems to me from observation.
I think the OP uses the word “justify” in the classical sense, which has to do with the idea of something being “just” (in a mostly natural-rights-kind-of-way) rather than merely socially desirable. The distinction has definitely been blurred over time, but in order to get a sense of what is meant by it, consider how most people would find it “very hard to justify” sending someone to prison before they actually commit (or attempt to commit) a crime, even if we could predict with arbitrarily high certainty that they will do so in the near future. Some people still feel this way about (at least some varieties of) taxation.
That could help explain the wording. Though the way the tax topic is addressed here I have the impression—or maybe hope—the discussion is intended to be more practical in the end.