The Ethical belief that there are absolute standards against which moral questions can be judged, and that certain actions are right or wrong, regardless of the context of the act.
So an Absolutist would say that stealing is always immoral, regardless or whether you are trying to feed your starving family, killing can never be justified and adultery is always forbidden. Even if goodness does come about from your action it is still not justified.
At first glance this seems pretty straightforward and a great way to do Ethics - we all know where we stand on an issue, we would know how others were going to act and judgements on morality would be totally clear cut. This allows us to write documents such as the declaration on human rights and to judge evil dictators who cause atrocities to their peoples. Simple...
For me the most pertinent problem with Absolutism is that life is not that simple. Kant drew attention to this such problem himself in Critique of pure reason; what if a crazed axe-murderer came to your front door and asked you where your father is? You could lie – many would say you should lie – but imagine if everyone in the entire world lied all the time. If everyone lied, there would be no “telling the truth” and, thus, no real lying. As the law is logically contradictory, you have a perfect duty not to lie. You have to tell the axe-murderer the truth, so he can go and kill your father. How can this be right? It’s in situations like this that strict ethical systems with specific decision procedures tend to fall apart. Morality is simply too complex and too full of exceptions for these theories to ever fully work.