In ethics we talk of the difference between 'selfishness' and 'altruism', and although it is frequently acknowledged that these terms are very elusive, we are to a great extent dependent on them for moral discussion.
On the surface of it, a straightforward reading of the dictionary has the case set out plainly.
self·ish adjective \ˈsel-fish\: having or showing concern only for yourself and not for the needs or feelings of other people
al·tru·ism noun \ˈal-trü-ˌi-zəm\ : feelings and behaviour that show a desire to help other people and a lack of selfishness
However, there's a sense in which these definitions can only be read plainly if we were discussing, say, animal subjects--subjects which have a clearly defined 'self' to which they can clearly be concerned with benefiting or not within a given activity. Animals have this as they are strictly programmed by evolution. They have a 'self' (using the term loosely) amounting to a biological entity looking to survive and replicate, as a biological entity. This sets out clear boundaries in which activities such as eating when hungry or finding shelter are self-preserving, while activities such as grooming another or helping another eat when they are hungry are other-orientated.
Humans are a different kind of creature, we are programmed by evolution only in a weak sense, and we are in a much stricter sense programmed by values. We have selves that are mental, which exist in self-selected ideas, and as such are malleable. We can learn, we can develop preferences, and we can change our minds. What is at one point unselfish can become selfish merely by shifts in our ideas. And therefore, there's a sense in which we can never become less selfish in the pursuit of altruism. If a person is motivated by 'wanting to win the football match' this notion may entail 'wanting to motivate the team', 'wanting to play your best', or 'wanting to give the crowd a good time.' Each action can be interpreted fairly as both selfish and altruistic. Although each can be seen in a sense as generous, they are not idly or purposelessly giving, they serve some desire of the self. This veil of selfishness to our actions continues to apply to most human intentions, even charity.
The lines between altruism and selfishness are blurred by our existence through the mental in which 'us' and 'the outside world' can be intimately intertwined by values. In the extreme, selfishness can manifest itself in form of dying for a cause or a loved one.
Under an Objectivist perceptive, this renders talk of altruism redundant, with altruism standing out only in instances in which coercive pressures precede generosity. But it is not evident that, if this be so, by the same token talk of 'selfishness' shouldn't becomes obsolete. If we find ourselves in a situation where one can say 'I changed my mind drastically from being selfish to being selfish', the term is hardly descriptive.
But of course, all of this misses the point. Practically speaking when people speak of 'selfishness' being good or bad, or 'altruism' being good or bad, they're really being used as umbrella terms for some handy rules of thumb to help guide us in selecting and reviewing our values.
selfishness is good entails ideas like: selfishness is bad entails ideas like:
it's al-right to enjoy yourself consider long term consequences
your property is your own the world is better when you don't hinder others
great innovation follows doing you own thing
altruism is good entails ideas like: altruism is bad entails ideas like:
human life is valuable your life is as worthy as another's
generosity enriches the soul you needn't become a willing slave to others
But the terms offer nothing more comprehensive, and certainly can't profit us in a one verse the other framework.
To decide between values we require much more sophisticated ideas to guide us.