I have some better ideas to increase GDP, using the author's chain of reasoning.
1. Use the military to break every window in every major city. This will force consumers to pay money to window manufacturers, thus increasing GDP!
2. Rob every poor person at gunpoint, and distribute all of the money to someone interested in funding a giant hole digging expedition. It will increase the GDP!
3. Threaten every rich person with the following ultimatum: "give me 50% of your money, or I will kidnap you from your family and lock you in a small cell for several years". Distribute the money to the poor, who will consume more goods, thus increasing GDP! <-- This is just a restatement of the author's position, since rich people who refuse to pay for a re-distributive tax are literally sent to prison.
In all cases (i) the economic fallacy is equating an "increase in GDP" with an "increase in wealth" and (ii) the moral fallacy is assuming it would be justified to take people's money from them without their consent.
In the long-run, it is the supply-side that increases societal wealth (not the "demand-side"), since long-run wealth is generated by entrepreneurs and investors who take risks to coordinate economic activity and invent new technologies. New technology, especially, is created by investors & entrepreneurs on the supply-side. So even if it weren't immoral, redistributing wealth from suppliers of capital and technologists to consumers doesn't actually create any new wealth. It is instead literally the consumption of wealth made by the suppliers of it!
The moral case against redistribution is the following argument: (i) it would be wrong for me or my gang to personally rob you of your money, even if I/we had noble plans for how to spend it; (ii) there are no morally relevant differences between individuals doing this and the state doing this, therefore, (iii) forceful redistribution of property is wrong. The details (and nuance) of this argument are supplied in Michael Huemer's "The Problem of Poltical Authority", which I highly recommend: https://www.amazon.com/Problem-Political-Authority-Examinati...
Michael Huemer, The Problem of Political Authority , p. 177:
> Libertarian political philosophy rests on three broad ideas:
> (1) A nonaggression principle in interpersonal ethics. Roughly, this is the idea that individuals should not attack, kill, steal from, or defraud one another and, in general, that individuals should not coerce one another, apart from a few special circumstances.
> (2) A recognition of the coercive nature of government. When the state promulgates a law, the law is generally backed up by a threat of punishment, which is supported by credible threats of physical force directed against those who would disobey the state.
> (3) A skepticism of political authority. The upshot of this skepticism is, roughly, that the state may not do what it would be wrong for any nongovernmental person or organization to do.
There is a kind of deontology called "Moderate Deontology", which says there are moral rules, but that these rules can be overridden in case of extreme consequences. This is in contrast to other forms of deontology, which may not consider consequences at all. This is a highly intuitive normative theory because in common sense morality, both rights and consequences seem morally important. There are obvious cases where the ends do not justify the means... unless the ends are severe enough, that is.
On this view, once you establish the 'rights' (like to property, and to not be stolen from), then their appeal to 'hospitals' is an appeal to an extreme negative consequence. You don't have to show that no-tax funded hospitals are better than tax funded ones. Only that a society without tax will sufficiently be able to provide health care to its general population -- in other words, that it wouldn't completely break down into a healthcare hellscape. Additionally, the burden of proof is on them to show that the consequences would be devastating (and usually they cannot bear that burden. Usually, they are highly ignorant about the specific topics at hand.)
Also, and I cannot stress them enough, appeal to moral premises they already accept, like that it would be wrong for non-governmental entities to steal money to provide [insert service here], and then challenge them to provide the morally relevant difference between a non-governmental agent and a governmental agent doing that thing. If they cannot provide that difference, then it is irrational for them to accept one while rejecting the other. (This argumentation strategy is employed by Michael Huemer in his book "The Problem of Political Authority" )
If they like philosophy or ethics I like this https://toptalkedbooks.com/amzn/1137281650