"K J" has these comments about a recent issue of The Quaker Economist:
This is an anti-economic idea. First of all, there are no subjects of study which are "squalid". To say that is to expose ignorance of what economists actually do. Economists study spontaneous order. To suggest that we shouldn't study something is to suggest that economics should not exist, as a profession, as a science, as a way of thinking.
Second of all, the mere existance of external benefits is not, a priori (and since K J rejects the idea of studying the issue because doing so is "squalid", they don't want there even to BE an postori) reason to spend coerced money on the source of the positive exernalities.
At a minimum you should ask the question "Will the recipient of the benefit pay for it anyway?" before deciding whether taxation is necessary. If they will, then there is absolutely no need to take money from other people and spend it against their wishes. For taxation by definition is spending money against people's wishes. If they wished to spend the money, they would do so with no need to threaten to hurt them if they don't.
Taxation is violent. You would be surprised how many leftists oppose war in the name of justice but promote violence in the name of justice. Poor justice, to be used and abused so!