"Man vs. Machine": The Rasbotham Theorem

I am, from the bottom of my heart, a Friend to the Poor. I wish to plead their cause, and to speak in their favour. I feel tenderly for the poor man and his family. And, if my heart does not deceive me, I would do, I would suffer any thing for their welfare. Led by no other principle, but regard to the Poor, I now wish to enter into free and friendly conversation with you, my poor but esteemed friends, on the subject of our machines. And in order to do this to the greatest advantage, I will first lay down some things necessary to clear our way to the point, and then endeavour to answer the question, of the usefulness or injuriousness of machines for shortening labour, particularly in the Cotton Manufacture.

1. The interests of the poor should have the highest priority (after all, what would become of the rich if there were no poor people to till their grounds, and pay their rent?);
2. There is not so great a difference between the real interests of the rich and the poor;
3. Trade is a large and difficult subject that requires deep thought, long study, extensive reading and large experience to form a true judgment;
4. Machines distinguish men in society from men in a savage state. There are many examples showing how machines invariably benefit people;
5. All improvements at first produce some difficulty but many receive the benefit while only a few suffer, probably not much and hopefully not for long (they should be grateful for the opportunity to make a sacrifice for their fellow man);
6. Trade will find its own level. Those thrown out of their old employments will find or learn new ones. Those who get a disproportionate gain will soon find many rivals and lose their temporary advantage;
7. There is a disposition among people to be unduly alarmed by new discoveries;
8. Even if machines (or globalization or the hypertrophy of the finance sector) are evils they are necessary evils. We might as well make the best of them;
9. This would be a prosperous time for the poor, if only they weren't so inclined to carry their money to the alehouse;
10. Anyone who disagrees with the above truths is an irreligious, conscienceless scoundrel; and (drum-roll),
11. That "there is only a certain quantity of labour to be performed" is a false principle.

The above propositions are not a random collection but a mostly faithful (if occasionally sarcastic) enumeration of Dorning Rasbotham's main points in his 1780 pamphlet, Thoughts on the Use of Machines in the Cotton Manufacture, whose unique contribution and enduring legacy consists of point #11, which has come to be known as the... now, what was the name of that fallacy?