but it might not.....what i was getting at is why would someone choose to suffer when it causes no enjoyment?
This is an important question since it touches on the heart of some essential differences between different sorts of ethics. Thank you for asking it.
Unfortunately, in modern culture there is a strong influence from the Age of Enlightenment on what is viewed as the complete life of the individual -- what is most often called "happiness". The popular view, and the one often attributed to atheists (that is, when they aren't being tarred with the brush of nihilism), is that happiness is merely a series of pleasures or "enjoyments", essentially a sort of hedonism. The human good is associated with these pleasurable feelings alone, and this leads to a purely instrumental way of viewing the actions of the individual.
Chosen actions are seen as mere means to enjoyments, and not as ends-in-themselves. Reason is seen as "the slave of the passions". The activities of one's life tend to be seen as a means to future moments in time, and not having much value in themselves. It is no wonder that life can seem meaningless in such a scenario, since one's actions are a series of means stopping abruptly in death. The final end seems perpetually out of reach, and is then denied, making one wonder why the means mattered at all.
And yet this is not the only way that naturalists have to look at life. In the eudaimonist view, enjoyment is
not the essence of the good of the human individual. It may be one ingredient in the mix, but it isn't the final end of human living.
Chosen actions can be a constitutive part of (not merely an instrumental means to) the ultimate end of human life, which is the flourishing (the personal growth, maturation, and self-actualization) of the human individual across the individual's entire lifespan. As Aristotle said, "One swallow does not make a summer, neither does one fine day; similarly one day or brief time of happiness does not make a person entirely happy." (Understand happiness in this quote to mean flourishing, not mere feelings of pleasure or enjoyment.)
Someone living in the eudaimonist fashion, as I strive to, may appreciate pleasure, and may seek it out in moderation, but this is not what one lives for, nor is it what one values above all else. Enjoyment has a legitimate role to play in the flourishing life, but it not what flourishing is, even if it is normally entailed by this as a byproduct.
Life is much like a work of art. I'm tempted to say that it is precisely a work of art. It is a creation, one's self-creation. If you've heard and understood the expression "diamond in the rough", you will know basically what I mean.
A picture is worth a thousand words:
The final end of one's actions is one's life as a whole: complete, integrated, and harmonious. The integrity of the art work is of paramount importance. This isn't to say that one should never make mistakes, which would be next to impossible. But it does mean that living in truth to one's true nature, which includes one's highest potentials and the logic of one's development, is far more important than mere enjoyment.
And this means that, while in ordinary circumstances one's actions tend to lead to enjoyment and more life ("Live long and prosper, Spock"), there are times in which the best course of action involves putting one's life at risk, including the clear expectation of losing it.
But this is losing one's life in order to save it. As I said, the integrity of the artwork is of great importance. People will die sooner or later. It is better to have ended one's life true to one's principles and nature, than to live a long and self-betrayed life. There are things worse than death.
And so, while I don't think that people should throw away their lives too casually, it just might be the case that the act that perfects and completes a particular individual's life is to end up dying to save a child from death. It could be an act of heroic integrity.
This is the answer to your question of how a naturalist might possibly do such a thing and see the act as justified. I personally think it is great philosophical improvement on popular naturalistic notions of happiness and the human good.
eudaimonia,
Mark