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...
I'm just about to finish up _The Problem of Political Authority_  and the author (Prof at Colorado University - Boulder) gives the social contract an _excellent_ rundown.
TL;DR: There is no social contract. It's a politically useful idea not rooted in moral law.
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