If one believes there is no actual life after death, and everyone dies eventually, then all that survives anyone is their legacy, so dying sooner rather than later in exchange for a greater rather than lesser legacy makes a kind of rational sense.

Military service is not generally a great way to leave a positive legacy, though.

Isn’t it enough if someone just feels good about sacrificing themselves? So they are not getting any rewards after the sacrifice (because they don’t exist anymore) but rather before and during the sacrifice.

If one believes there is no actual life after death, and everyone dies eventually, then all that survives anyone is their legacy, so dying sooner rather than later in exchange for a greater rather than lesser legacy makes a kind of rational sense. — Pfhorrest

How to you explain greater legacy as a consequence of dying sooner? How would the length of one's life have anything to do with "legacy?" Does it relate to a culture of honoring those who sacrifice their lives to their country? Why should anyone care about legacy?

Because people like that understand that the continual existence of certain people is worth more than their own continual existence. Think of it another way. If no one's else's lives hold any import to you, why not kill everyone if you could get away with it? I believe that if most people were given this option, they would not do it.

How to you explain greater legacy as a consequence of dying sooner? How would the length of one's life have anything to do with "legacy?" Does it relate to a culture of honoring those who sacrifice their lives to their country? Why should anyone care about legacy? — Nils Loc

By "legacy" I mean whatever impact you leave behind on the world. If you can do something good with your life, but doing that will make it shorter, I can see why someone would choose that.

Say you have a choice between:

1) live another 40 years until your natural death, and shortly after that, events already in motion (details unimportant) will lead to the collapse of civilization, worldwide suffering, and the eventual (but not too distant) extinction of all life on Earth.

2) do something that will prevent all that and allow life and civilization to flourish far into the future, at the expense of you dying in the process, 40 years sooner than you otherwise would have.

I can see it being a rational choice (but by no means an obligatory one) to pick option 2.

But as I said before, I absolutely don't think military service is "doing something good with your life", the likes of which justifies sacrificing the rest of it. I'm just talking about the general principle, not this specific case.

I can see it being a rational choice (but by no means an obligatory one) to pick option 2. — Pfhorrest

It's hard to rationalize those choices in your scenario, especially if we multiplied actual life- scenarios . One might see the future unchangeable due to massive historical forces. How much does one person's voice/actions/vote count in the course of this flow. This would help one to choose life over the unknowable effects of sacrifice. But there are folks who know how powerful one vote/action/choice is in the course of saving lives but I can't imagine there is much vacillation about it. One takes action and that is just an expression of one's moral character. Or one is conscripted (or follows the order in the chain of command) at the cost of being made a coward by one's peers.

but how does one justify risking ones life for any cause whatsoever without knowing what if anything may exist after life? — TiredThinker

Perhaps not about any afterlife, but about this life. Try reading the Iliad. (Lattimore trans. best.)

Then out spake brave Horatius,
The Captain of the Gate:
To every man upon this earth
Death cometh soon or late.
And how can man die better
Than facing fearful odds,
For the ashes of his fathers,
And the temples of his gods”

― Thomas Babington Macaulay, Lays of Ancient Rome

I think about legacy often enough. But statistically after 200 years no matter what we do there will be no record we ever existed. And even if we define our deeds as good we have to tie our deeds individually to the value of being human in general? We certainly do much for ourselves, but what do we do for our world?

I do not wish to underscore the noblest of ideals held by many in the military, but how does one justify risking ones life for any cause whatsoever without knowing what if anything may exist after life? — TiredThinker

How would anyone take a risk at anything, because obviously nobody knows if there is life after death?

Yet people do various things that are dangerous understanding it's necessary... and simply weigh the risk involved to what otherwise would happen without taking a risk.

We take risks with greater survival in mind. A mouse without dopamine in their brain won't feel motivated to eat food directly in front of them and die.

How much does one person's voice/actions/vote count in the course of this flow. — Nils Loc

Despite the fact that game theory has been rendered mathematically and logically systematic only since 1944, game-theoretic insights can be found among commentators going back to ancient times. For example, in two of Plato’s texts, the Laches and the Symposium, Socrates recalls an episode from the Battle of Delium that some commentators have interpreted (probably anachronistically) as involving the following situation. Consider a soldier at the front, waiting with his comrades to repulse an enemy attack. It may occur to him that if the defense is likely to be successful, then it isn’t very probable that his own personal contribution will be essential. But if he stays, he runs the risk of being killed or wounded—apparently for no point. On the other hand, if the enemy is going to win the battle, then his chances of death or injury are higher still, and now quite clearly to no point, since the line will be overwhelmed anyway. Based on this reasoning, it would appear that the soldier is better off running away regardless of who is going to win the battle. Of course, if all of the soldiers reason this way—as they all apparently should, since they’re all in identical situations—then this will certainly bring about the outcome in which the battle is lost. Of course, this point, since it has occurred to us as analysts, can occur to the soldiers too. Does this give them a reason for staying at their posts? Just the contrary: the greater the soldiers’ fear that the battle will be lost, the greater their incentive to get themselves out of harm’s way. And the greater the soldiers’ belief that the battle will be won, without the need of any particular individual’s contributions, the less reason they have to stay and fight. If each soldier anticipates this sort of reasoning on the part of the others, all will quickly reason themselves into a panic, and their horrified commander will have a rout on his hands before the enemy has even engaged. — SEP

Just going to say it here; right now my soul is more important to me than all the rest of the US combined. Maybe in 30 years when immortality is clearly off the table might I be more partial to the idea of sacrificing myself for the greater good. Personally though I don’t think joining the military is the way to go. The military is just a social program for expendables diluted into thinking their country deserves patriots.

The ten thousand things rise and fall without cease, Creating, yet not possessing, Working, yet not taking credit. Work is done, then forgotten. Therefore it lasts forever. Not exalting the gifted prevents quarrelling. — Lao Tzu

People risk their lives for one-another every day all over the world, because they understand in their bones that we are interdependent and cannot afford to be wholly selfish. It needs no more justification than a cold beer on a hot day.

We do some good for each other, but rarely do we give it all. If a monkey eats poison berries it starts choking and the troop of monkies imitate that in case they too have eaten the same thing. These things are evolutionary mechanisms. They aren't truly altruistic behaviors.

but how does one justify risking ones life for any cause whatsoever without knowing what if anything may exist after life? — TiredThinker

There may be a good reason behind what you're saying but I think you have it backward. The notion of sacrifice involves a loss. If there's an afterlife, nothing is lost and sacrifice becomes meaningless.

But monkeys have also been shown not to make the "it's a frickin' big snake" call if there are no monkeys near them to hear it. (Don't have a citation handy, sorry.)

I am assuming we can't prove an afterlife. Therefore a loss of life is a loss of everything.

I am assuming we can't prove an afterlife. Therefore a loss of life is a loss of everything — TiredThinker

Then you've answered your own question, right? For sacrifice to be a meaningful concept, there should be no afterlife and, as far as I can tell, no evidence for an afterlife exists. In other words, a soldier giving his/her life for another counts as a sacrifice for all intents and purposes.