Reason and Sacrifice
When we consider how humans have evolved, what we have needed to overcome and where we are today, it becomes clear that self-sacrifice does not factor into that equation. Humans have observed that self-sacrifice runs contrary to survival instinct. Exchanging something of value for something of lesser or no value can quickly lead to famine and loss. People must learn to be civil and conduct themselves with integrity, but the very basis of modern society is the idea of exchanging value.
Altruism is a concept that relies heavily on the idea of self-sacrifice. Living an altruistic lifestyle means living for other people, which runs contrary to the basis of our human nature. If early humans had gone out of their way to help everyone, we might not have made it out of the Dark Ages.
Altruism is a nice concept to consider morally speaking, but it is not sustainable because it is irrational.
Consider what motivates altruism.
Is it spirituality? Spirits do not exist in the physical realm, and no evidence exists that they can manipulate the physical realm with certainty.
Is it because the group agrees? Parts of the world consider lots of horrible things like beheadings to be “ok.” Should this justification be used for those other atrocities as well?
People do need help, that’s true, but individuals cannot save the whole of everyone who needs the help. This is why we have charities that focus on specific problems. More importantly, humans must learn to accept the consequences of their actions, which can include poor choices.
If we accept that the ego, the self, is guiding us, then there is only self-interest left. We can perform charitable acts, we should care for our fellow man, but there is nothing in our nature that drives us in this direction.