If someone were presented the option to permanently undo a major aspect of their own life, and "rewrite history", would it be morally wrong to do this? Consider the following scenario: a person dedicates their life to an ideal such as justice or peace or any morally sound ideal such as those. They sacrifice so much of their time, energy, life, and sanity to the fulfillment of this ideal. However, due to unforeseen circumstances their actions lead to an outcome they were unsatisfied with. Would it be wrong for this hypothetical person to change their entire life to avert this terrible fate?

Before I could consider the ethics of this scenario, I'd have to satisfy myself that it's a coherent scenario. Let's call the person in question "Jane." The scenario seems to require that something like the following be true: "Jane sacrificed much of her time and energy to achieve justice, but because her sacrificial actions led to an unsatisfying outcome Jane didn't sacrifice much of her time and energy to achieve justice." I can't see how such a scenario is comprehensible enough to be assessed ethically. The question also arises whether Jane's sacrificial actions contributed so much to Jane's identity -- to who she now is -- that it's incoherent to ask what Jane's life would be like now had she not made those sacrifices: we wouldn't be asking about Jane but about a numerically different person.

Why is such a high value placed in reading the "Classics"? It's one thing to honor the past and honor the fact that, but for those who came before, we wouldn't be where we are today, and another thing entirely to pretend that those "classic" thinkers and thoughts of the past are worthy of the scrutiny of self-respecting truth-seekers today. If I'm being honest, the Pre-Socratic writings are simply idiotic by today's standards, claiming matter is all "water", or "fire", or some other random element. Leibniz, Spinoza, and those guys aren't any better. None of them had even the most rudimentary concept of physics. JS Mill and Kant read like some High Schooler, discoursing at length about Happiness and motivation without even a whiff of suspicion about the basic facts of psychology, treating those terms as if they were transparently obvious, monolithic concepts. Even an idea like the more recently vaunted Veil of Ignorance seems ludicrously vulnerable to someone of even mediocre intelligence, like me. It...

I can't resist piping up to defend Rawls's Veil of Ignorance. In A Theory of Justice , Rawls anticipates and rebuts the questioner's objection. The deliberators behind the Veil of Ignorance are choosing the most general principles of justice that will govern their society, and hence they have no basis for the specific prediction that a given principle will make "90% of people happy and 10% utterly miserable": as Rawls says, behind the Veil of Ignorance such numerical estimates "are at best extremely insecure" (p. 154). Given that insecurity, Rawls argues that it would be irrational for you to risk being among the utterly miserable, particularly if your gain in happiness (compared to what you'd experience in a less unequal society) is small compared to what you'd lose if you end up among the utterly miserable. His argument may not be conclusive, but I don't think it's as easily dismissed as the questioner suggests.