So, by popular demand - ok, so ONE person asked for it... here's some thoughts on the word 'should.'
Whenever we use the word 'should' we are making a moral or ethical statement.
Let us suppose that my friend Justin has cancer. Now he's a young man with a lot to live for. Now suppose that in my pocket, I have the cure for cancer, should I give it to him?
I don't think many of us will have any hesitation in giving an answer to this question (whether you know Justin or not). Of course I should. But why? Well, because the notion that to save life is good is embedded into our thinking. (It is for this reason that healthcare is primarily a moral pursuit and only secondarily a scientific one.)
It order for the word 'should' to have any meaning at all there has to be moral absolutes. That is things that are right and things that are wrong. . That does not mean necessarily that any one of us necessarily knows what's right or wrong in any or every particular situation but that such things do exist. A lot of people argue that morality is a matter of opinion or even about majority views. I have serious issues with this.
To take two extreme examples, the Nazis thought that exterminating the Jews and homosexuals and Gypsies and the mentally ill was right. Similarly, if you were to take a poll of the Maassi tribe in Kenya and Tanzania they would say that female circumcision (or female genital mutilation) is acceptable and a traditional ritual. In both cases I think they are clearly wrong. These are things that should not be done.
The philosophical arguement is one about atheism vs theism. The reason for this is that in order for there to be any such thing as more absolutes there must be an absolute bench-mark of morality which we call God. If God does not exist then there are no moral absolutes. Many people will argue that there aren't moral absolutes. If this is true then the word should is meaningless, there is no morality and we should (sic) do whatever makes us happy.