Let's suppose we know what is in everyone's best interest.
If someone is sick, we know that it is in their best interest to seek medical attention, if they are starting a business, it is in their best interest to quickly pay off the cost of their company through a number of different means, and so on and so on. Heck, if you want to buy a mansion and someone offers you ten million dollars to buy it, it's even in your best interest to accept the money.
Now, let us suppose that we are being forced to accept things that are in our best interest. If you're ill, you are forced to go to the hospital, and if you're starting a business, you are forced to accept funding to help make it easier to pay off the cost of the business you just started. If you want to buy a mansion and someone is willing to give you the money to buy it, you must accept it.
So let me ask you this. Should we be forced to accept what is in our best interest? If, for one reason or another, you do not want to go to the hospital, or you do not want funding for your business, should you be forced to accept it?
Should someone have the power to 'help' you, even if you don't want it?
It depends, 'helping' you by buying a mansion is like a gift, it only has an effect on you if you want it to, you can go about your daily life ignoring it and nothing changes. In a case like that, yes, some one should have to power to help you, as they can't force you to accept it. Helping by forced hospital care, no, as that has a drastic impact on your daily life.
Nobody should ever be forced to accept something, even if it would greatly benefit them.
Choice should always be given, even if the consequences for making the choice that others don't want you to greatly outweigh the benefits of accepting the choice that they have pushed on you.
It's your life, you should be able to do what you want with it.
The way you are describing "self-interest" is incorrect (but you know that). Or rather, it is imcomplete. It's how a computer might describe self interest: maximizing personal satisfaction. From a computer's perspective, going to a hospital when you are sick is obviously in your self interest, because health is preferable to illness.
But that's not how all humans will look at it, and since we are talking about a human's interests, we should address the issue from their perspective.
In this case, a human might not regard staying in a hospital to be in their best interest. The emotions associated with being forced into a hospital - lack of free will, paranoia, defeatism - could outweigh the benefits attained through increased health. Logically, these emotions are not valid, because they are unfounded and prevent oneself from benefitting from medical care.
So the question you are actually asking is: Does the government get to decide which emotions are valid and which are not?
Your best interest might not be the interest you like the consequences of, the best interest furthers your life to the best way. The best way is defined by greed.
There is always another failure or success around the corner; the thing that determines whether it is a failure or success is the options you have in it.
No-one should be able to force you to do anything, unless it affects other people in a bad way. Unless you are mentally ill. That is the exception.
I almost agree with this. I think saying mentally ill is a bad description, as not all mental illnesses are bad for the person with them or the people around them. I think it should just be: You can do whatever you want, as long as you are not harming others. Although thinking about that leads me to the whole point of this thread, even if you are not harming them it might be against what they want... Hmm... Maybe it should be more like: You can do whatever you want, as long as you aren't harming others or forcing your will on them. That sounds better to me.
No, only the person itself knows what is in their best interest. The others might have good intentions, but this does not mean that you can force a person to do something against its will. There must be a reason why he does not accept their help.
And what if the one deciding what's in your best interest, decides that it is in your best interest to die? Who are you gonna give this power upon you? Why Shouldn't we make mistakes? Seriously, wasn't the OP a moderator, I would have thought this is a troll thread.
A doctor should ALWAYS try to save a patient's life, whether that patient wants to be saved or not.
This is precisely why we have things like DNRs. If a patient is in a position to die of an illness or other natural causes, it is illegal for a doctor to resuscitate a patient who has signed a DNR.
But the OP started with a given premise - that we have some sense or some method to determine what is "best" for someone. I think the problem is defining exactly what is meant by this. Is this posited society "All for one" or "One for all"? If someone is a drain on society, then it would be in society's best interest to simply euthanize that person. But this doesn't seem to be what the OP means - it seems to be focused on the individual's best interest. Still, we have a problem with definition. Are the things in my best interest just those things that will make me happy? This is likely not the case. Just to put this in a more approachable light, let's say my son is quite ill and has to take this disgusting medicine that he hates in order to get better. If we're just taking his best interest to be what makes him happy, then we have short term and long term considerations. In the short term, the answer is clear: he shouldn't take the medicine. It has no immediate effect on his health and he won't start feeling better for maybe a week. In the long term, the answer becomes murky. Sure, he'll feel better and live longer (we could assume his illness would kill him), but maybe he's going to end up spending the rest of his life as a destitute, hopeless, lonely bum. In this scenario, then, it would seem again like he shouldn't take the medicine.
So in order to understand someone's best interests, it looks like we would have to know the future - at least on some conditional level. But now the thought experiments just seems to come down to a strict form of utilitarianism, which seems to miss the OP's point completely.