The tale of the slave is an analogy and it works depending upon whether the underlying premises are sound, and it doesn’t work if the underlying premises are unsound.
I invoke it, too, because it highlights the problem of presuming democracy makes any result acceptable – and it’s a synopsis of the evolution of democracy. It’s a reasonable comeback, IMO, to people who suggest “well, when you voted, you agreed to be bound by the results, whatever they were, and we voted to expropriate you and use you for corvee labour, so you have no legitimate grounds on which to complain.” (Note that a lot of anarcho-libertarians – not all of them, but a lot – *do* accept this, and is a reason why they consider voting objectionable, and elections morally objectionable, and they will argue – I saw some of the arguments this cycle – that if you participate in the electoral process, you are signing the contract and have no grounds on which to complain about what is done to you afterwords, whatever that might be. So, they further argue, the only way to maintain your moral independence is not to vote. I emphasize though that this is only *one* argument for non-participation, among several that they have).
So we get back to Feser’s objection: His objection-analogy is based on contract itself. Which fits within Nozick (and Locke’s) “Social Contract”-based theory. But Feser himself is (no longer) really a social contractarian, either (and as he further elaborates, that becomes somewhat clear. But it’d probably be helpful to understand where he’s coming from by reading his books – which are actually very good, though he, IMO, left out a key half of a principle, which I’ll get to at some point). On that subject, we might invoke our gracious host’s video: https://www.youtube.com/watch?v=nTqEePlZiqk
And, taking off from that point, we can point out that while Feser says Nozick’s “Tale of the Slave” is “underdescribed,” so too is Feser’s counter-argument: Lets say for the sake of argument that I accept I have moral duties, including positive moral duties, that I did not explicitly choose. Just what are they? And if they are enforcable, by whom and how did they get the authority to enforce them? Note that I agree with Feser that we have enforcable moral duties that we are obligated to obey even if we did not sign a contract (and indeed even anarcho-libertarians agree with Feser – though they boil it down to one primary one: non-agression).
I’d suggest, btw, that one problem in Nozick, and Locke, is the social contractarian starting point, which led almost inexoriably to the Progressive conflation between “society” and “state” – as in “shouldn’t society do such-and-such?” by which they (the Progressive, at all times from their 19th century origins to the present) always mean “shouldn’t the state do such-and-such.” Yes perhaps we in society should do such-and-such but their is a missing logical step to leap from that to “it is done through the power of the state.” (I digress slightly, but IMO importantly).
I think Tom Woods, for example – a believing Catholic, just like Ed Feser – would agree that we have moral duties to each other, including ones beyond non-aggression. But that does not lead directly to the conclusion that these obligations are enforceable by a monopoly-power state. (note: I myself am not convinced of anarcho-capitalism. But I do agree that critics of anarcho-capitalism, or even minimalism – including Feser, a very good philosopher who should know better – skip steps in reaching their conclusions, and then “under-describe” what follows from their own conclusions).
Well, I didn’t get to everything, but this is long enough for a forum post. But the details of these things can get really long as you argue them through. Which is why, even though as a stand-alone the “Tale of the Slave” is incomplete, that doesn’t mean it’s not useful to invoke it in a discussion/debate with someone; it was always meant to illustrate an argument, so people can envision and grasp it better, not be entirely complete on its own. And that argument is that just because you’re allowed to drop your pebble into the bin with everyone else, that doesn’t mean your liberty is automatically respected and there is no grounds for you to complain when it is violated. You can, indeed, be a slave-with-a-vote and still be, in effect, a slave.