The slippery slope argument is old; I ran across it when looking up "poor white trash" to find a southerner opining in 1860 that if rich Bostonians allowed people to attack slavery, they'd wind up with (literal) communism soon after.
https://news.ycombinator.com/item?id=23599419
> "For (and mark well our words!) you, Sir, half priest and the other half demagogue, wearing the surplice and wielding also the secular arm of power, have been for a long time preaching a crusade against the rights of property--have taught men every where, that to deprive their neighbors of property valued at millions and millions of dollars, instead of being an infraction of the Divine Law and therefore criminal in the sight of God, on the contrary would entitle them to receive praise and honor in the present life, and insure to them in the life to come rewards imperishable. And upon what pretense, forsooth? Because your neighbors, as you claim, can possess no rights of property in men and women--in human flesh, and brawn, and blood, and brains, to use your own vernacular of cant. And so in truth they ought not in foro conscientioe, without making an equivalent return, either in the nature of protection, food, shelter, attention in sickness and the like; the most of which the Southern slaveholders are constrained by law to grant in return for the service exacted of their bondmen. But, you clamor, they do not return an exact and equal account--they charge too much for their kind superintendence and benevolent regard! Ah! Sir, it is just here that you have trodden upon an adder, which will in time turn and sting your Reverence. For, truly, the poisoned darts you have so resolutely hurled against the South will, rebounding, yet find a mark the archer little meant, and one close to your own hearthstone.
> Unconsciously to yourself, you have been advocating all this time only a new species of agrarianism. Unconsciously you have been sowing the wind, and sooner or later will surely reap the whirlwind for your pains. Already your laborers, your operatives, your journeymen mechanics and others, secretly moot the question: How it happens they remain so poor, while their employers are constantly growing richer and richer; build their marble palaces, educate their children in idleness and dissipation, and besides spend half their own days tuft-hunting and toad-eating upon the continent of Europe. Already, we repeat, this terrible question is being mooted in secret conclave; and should the time ever come when it shall be mooted openly--when loudmouthed and earnest men, fresh from the people, shall bestride Faneuil Hall, bawling for an equal and exact distribution to every mechanic of whatever craft, to every operative of whatever mills, to every laborer of whatever grade--bawling, we say, for an equal and exact distribution to the workmen of the net proceeds
of their combined labor; and denouncing in the same breath pampered capitalists, as so many lordlings growing rich on the earnings of the moiling and toiling poor, reaping where they have not sown, and gathering where they have not scattered; upon what plausible pretext will you, Sir, then seek to gainsay them? You will have none. Dumb and quaking with fear you would be constrained to acquiesce in their logic; for they would only use in their own behalf the identical arguments you have assiduously tried to impress upon their minds for ten years and more, in order to persuade them to interfere in the affairs of their neighbors."
They must've had a bit more time to write rants in the nineteenth century. With the benefit of hindsight, we can also see the naïveté of times which apparently expected consistency as a measure in political arguments.