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.
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.