Why ethics.

(Selfish,Ethics: Consider the generally prevailing definitions for the word)

What  usually is the reason given for the advice: 'don't be selfish'? Its just 'you shouldn't be selfish', or 'being selfish is bad'.
Why to help others? Coz it is a good thing.
Why give your seat to some old lady in metro? Coz it is good.
Be Honest. It is good.

I think these answers need a bit more explanation or maybe more.
How exactly could these 'good' and 'bad' things have started?
Obviously, if you help others, others will tend to help you, out of returning favor, or to make sure you keep helping the others. That is why it is a good thing. I used to feel bad when people said 'keep helping others, you never know hen you'll need somebody..', now I don't feel bad at all. I do feel good when I help some people,but I am not really sure of 'why'. Is it because I've been taught to feel good, or is it because I really do feel good. (I hope to get the correct answer asap!)

If you think only about yourself, why would anybody want to be with you!?
If you talk to somebody only when you need him (and he doesn't have anything to gain from you) why would he like you? That is why being selfish is a bad thing.

I have heard of people who say something on the face, but believe something completely  opposite! (i think we call them 'hypocrites'). Maybe they praise you on your face,for some uncountable things in you, but in reality hate you, and never tend to show it. That's like a crime! If somebody gets to know this about that hypocite, he is dead! People will stop believing him. That is why it is a bad thing.There is nothing wrong in doing this (just like nothing else is wrong), but it might only be bad for you. Since you hate that somebody, maybe you spill that out in front of somebody, then that somebody gets to know that you are a back-biter.. So your purpose (of, maybe, pretending to be good) fails!

If you are honest with people, those people will believe in whatever you say. They will trust you. There are moments when we feel the urge to lie, but that one lie might ruin the trust forever. Control yourself for that moment, and be honest. That helps in the future. (merko to accha bhi lagta hai, I don't know why. ) So you are being selfish.. but in a sense for which people won't hate you. That's why honesty is known as the best policy.
I also follow it. I have been doing it unknowingly since my childhood (age<=17) , and it always felt good. Now I also have some reasons. So feels better.

Save environment. That is for you! You will get better place to live in! That's why save water, electricity and stuff.
Donate blood. All ads which wanted us to donate blood always only told us to do it. There is this ad that came a few months before, it said 'Donate blood, kyunki accha lagta hai!' That's fine with me. You donate blood, ask everybody else to donate blood, that donated blood might just help you someday! (It is not because you are getting back the results of doing a 'good thing'!!)

Ye sab 'acchi aadatein' tabhi humare maa baap sikhate hain. Somebody might have started it, others might have followed. Maybe, slowly the reasons started fading away, and what remained was just 'good' and 'bad'. As a child, we were not allowed to question our elders. I expect that even they don't care about the reasons.
But now I think we should know why we are following some principles. In this context of ethics, the answer of  'why' (at least for me), is that we are selfish.
Or may be, as Ayn Rand says, some people wanted us to feel guilty, so as to gain power over us, so that we always look up to them for justification of everything... This explanation did come as a shock to me when I read The Fountainhead, but it does seem to be a correct explanation. And a bit too convincingly stated in the book. (That was in fact my favorite part!)

Similar explanations follow for murders, rapes, terrorism, child abuse and other stuff..

We  tend to forget these ethics when we really are in trouble, and then feel guilty. I don't think there is anything that should make anybody feel guilty... you just made it bad for yourself!