Jean-Paul Sartre had some interesting observations of man. He references free will in that we are who we will ourselves to be. We are what we make of ourselves. This in a sense is true but it seems to be said with an air of gloom about it. Ross explains that what we ought to do is produce the most good. This method at least helps the free will to choose the right road to travel. Sartre does go on to say that will is a conscious decision on the part of man. Man acts on behalf of all men, but this can be extremely difficult since not all men have the same moral views.
As is the case stated that two parties to an ethical dispute have similar moral values they might be able to resolve the dispute once the facts have been made clear. It is when the moral views are opposing that a suitable resolution may not be reached.
Sartre also speaks of God in his philosophies. He reports two viewpoints; one where God does not exist and how people view that. Without God, we have no value system with which to legitimize our conduct. He has an interesting viewpoint when he says that man is condemned to be free. Since man did not create himself, he is free, but on the other hand, since he was created, he is then responsible for his actions.
Sartre makes no excuses for man and feels that man should not make excuses for himself either. We need to be able to act and make decisions. Man should not avoid this necessary part of life. I think what he is trying to say is that we are free because we are born despite the fact that we had no say in whether or not we were born. It is our duty, simply by being born, to live a responsible life and chose the right actions. Maybe this is what he means when he says man is responsible for one another.
Nietzsche has some philosophies that are difficult to accept and that is that the noble folks are superior to the slave-morality folks. The noble folk have the master morality and the common folks represent the salve morality. The nobles determine values. Good is noble and bad is the root of slave-morality. He places a lot of credence in man without God and without religion. He seems to have completely contrasting views from the other philosophers. I tried really hard to like this man's views, but somehow I am very opposed to his thinking.
When trying to define good and bad, it becomes almost comical for G. E. Moore, as when he said a book is good. Another philosopher said the word "wrong" was not the proper word to describe an action. It seems the philosophers were searching for the proper terminology, and probably they were all correct, but just looking at morals from different perspectives.
I am not sure that there is no way to define good. I would rather say there is a multitude of ways to define good. We can probably write several papers on just the definition of good.