A taxonomical analysis of dilemmas faced in everyday life yields just three major types of moral cliffhangers that man experiences in various incarnations. Let's explore these dilemmas through an analogy.
Consider two men hanging off the edge of a cliff. Let's call them person A and person B. In five minutes both of them will lose their grip and die. It will take three minutes to save either person. So you can save either A or B.
The first kind of dilemma is one of making a choice. Should you pick A or should you pick B? In picking either A or B, besides saving someone's life, you must express an opinion. Should you publicly express an opinion that hitherto had been private? One may decide that saving one life instead of losing two is worth outing one's opinion. On the other hand, one may very well take the opposite stance as well.
Let's suppose you decide to save A's life. The second kind of dilemma arises when you realize that in saving A's life you will cause the immediate death of person B. In the first dilemma, B's death would have been independent of whether A lived or died. In this case, their survival and death is correlated. B would have died anyway in five minutes. But in saving A, you cause the death of B instantaneously at the end of three minutes. In other words saving A is causal to the effect of B's death. If you still choose to save A, it means not only that you want to save A, but also that your are ok if B dies as a result of it. In the first dilemma you only expressed a preference for A over B. You could plausibly argue that you would have saved B if only you had the time. In this case, in saving A’s life you indicate that B's life is of no consequence to you.
A third, even more pathological, dilemma arises when you discover that in order to save A, you must first push B off the cliff. You discover that the reverse is also true. To save B, you would first have to kill A. What do you do now? If you don't do anything, both will die. Should you kill B to save A? If you do, then you have stepped further ahead from the second type of dilemma. In the first dilemma, you didn't have the time to save B. In the second, you were indifferent to B's life as long as A was saved. But in the third you are willing to kill B to achieve your goal of saving A. You have essentially let the cat out of the bag. Not only do you prefer A, but you also despise B.
A and B need not be individuals as presented in the examples above. A and B could represent a group of children, a company, a wild life preserve, an embryo or even one's own life. Like the colors red, green and blue, these dilemmas are the primary colors of human doubt. One can mix these dilemmas through a simple mechanism: probability. Suppose that in the third kind of dilemma, killing B would only give you a 60% chance of saving A while there is an 80% chance that both would die if you take no action. Would you still kill B to save A?