Apologies for not answering this sooner, first I had to think about it and then I got caught up in some very intensive Football Managering.
There is no simple answer to your question, without treating you like a child yourself. Today we know that there are many different ways to look at morality - in a spiritual sense, in a darwinian or anthropological sense or in a rebellious Nietzschean sense. Knowledge of these later perspectives makes it difficult to believe in the former, initially at first.
The modern view, divorced from damnation, is that we need morality because we need to live together. No man is an island and we take our strength from the strength of the tribe. We have developed an instinctive liking for equality - I say instinctive because it operates on an instinctive basis, in the same way as say, our dislike of incest is instinctive and this subconscious belief in equality colours a lot of our conscious moral reasoning. The belief in equality developed during our days as hunter-gatherer tribes. Those days vastly outnumber the time that we have spent as farmers. Key elements of this morality may pre-date language. A lot of what we consider “reasoning” is language laying a cloth over the instinctive hunter-gatherer tribal morality.
We can’t yet say scientifically what the axioms of this morality entail but we can make a good guess that it has at least two key foundation stones - firstly that those who make an equal contribution to the tribe should be rewarded equally and secondly that all the weaker members of the tribe who don’t contribute as much still have value and should be protected and kept alive as far as practicable. But these moral axioms are instinctive emotional reactions, like hunger or a fear of snakes, not mathematical values that can be weighed up like gold and millet.
(The application of these axioms was always highly flexible and culturally and situationally relative. There are hunter-gatherer tribes where most of the old and vulnerable end their lives by being murdered by younger members of the tribe when they start to become a burden and Herodotus in his Histories records nations where every old person is ritually sacrificed by their children when they reach a certain age. He writes that this was considered the happiest possible death and was a cause of great celebration for all the family).
In the modern world, post agriculture, post feudalism and post Adam Smith, we have devised ways of structuring our society that are much more complicated than our hunter-gatherer ancestors, with their instinctive hunter-gatherer morality, could have anticipated. The birth of agriculture brought a need to control flooding, which led to desire for monarchy and more recently capitalism and the idea that a rising tide lifts all boats has led to further tolerance of inequality. There is also the thought that we shouldn’t take money from the rich because tomorrow we could be in their shoes. Our evolved simple instinct for equality just can’t handle that level of societal complexity or keep pace with the level of change.
Sometimes the young parents who most publicly espouse the values of equality are the same who are most tolerant of their kids disregarding those same rules. Middle-class parents, feminist and woke with single-child families where the kid is allowed everything (especially if he is a boy). The yummy-mummies raise their boys to be little napoleons with a frightening sense of self-entitlement.
So where does that leave a young father like @Thomas_Brady , floating in this crazy world, trying to teach his baby daughter not to be a bitch but lost. He is wondering what kind of daughter he really wants to raise. And why?
Firstly, let’s make the cynical arguments for altruism. We all need to live together. Specifically, you need to live with your kids for the next 18 years. If you have multiple kids you’ll have to live with all of them and they will have to live with each other. This means that your daughter will have to be share and be nice or else your entire life will be insufferable shit. So pragmatically you will either teach your daughter to share or you will slowly go insane.
@Malarkey sometimes (always) namedrops John Rawls - a famous political philosopher from the 20th century whose entire argument was based on the idea that if we are asked to divide up a cake and we are blind as to what slice we will get then we will always choose to divide it equally. There’s much to be said on this as the foundation of a political philosophy but as a stand-alone statement it is probably true.
There are huge arguments for altruism outside of the nuclear family though - studies have shown that the two personality attributes which most contribute to success in large business hierarchies are high levels of assertiveness and high levels of conscientiousness. On the surface these might be misunderstood as opposite qualities but in a strong personality they compliment each other in a special way.
Popular people are more likely to succeed and in the long run generous people who share and are not needlessly abrasive are more likely to be popular. You need to teach your daughter how to operate smoothly in social circles and you need to teach her early. Someone who doesn’t naturally share can’t form alliances as strongly as someone who shares easily and will be forever hampered.
But that’s not why I think you should teach your kid to share.
The real question here is why do you share? What does @Thomas_Brady believe in. Who does he want to be and why?
If the desire to share can be dismissed on darwinian or post-modern grounds, why not dismiss our greed and lust for power on the same grounds? We find ourselves entirely free to be whoever we want to be and to do whatever we truly believe.
For me, if we are separate from the other animals at all, that difference lies in our ability for altruism, for rational and moral discourse, to change our behaviour in the name of what is right. That is the essence of our humanity or at least whatever is good in our humanity. That is the ultimate freedom. Maybe even the only freedom. When that freedom is embraced a good life is its own reward.
Imagine how deeply impoverished your child’s life would be if she didn’t see the beauty of kindness. What riches could compensate for such a permanent loss? All the riches in the world are forever gloomy when the night is starless.
So you need to raise your kid to be the kind of person you want her to be. You need to ask yourself what you truly believe. What is your moral centre?