Consistency—the absence of contradictions—has sometimes been called the hallmark of ethics. Ethics is supposed to provide us with a guide for moral living, and to do so it must be rational, and to be rational it must be free of contradictions. If a person said, "Open the window but don't open the window," we would be at loss as to what to do; the command is contradictory and thus irrational. In the same way, if our ethical principles and practices lack consistency, we, as rational people, will find ourselves at a loss as to what we ought to do and divided about how we ought to live.
Ethics requires consistency in the sense that our moral standards, actions, and values should not be contradictory. Examining our lives to uncover inconsistencies and then modifying our moral standards and behaviors so that they are consistent is an important part of moral development.
Where are we likely to uncover inconsistency? First, our moral standards may be inconsistent with each other. We discover these inconsistencies by looking at situations in which our standards would require incompatible behaviors. Suppose, for example, that I believe that it is wrong to disobey my employer, and also believe that it is wrong to harm innocent people. Then suppose that one day my employer insists that I work on a project that might cause harm to innocent people. The situation reveals an inconsistency between my moral standards. I can either obey my employer or I can avoid harming innocent people, but I cannot do both. To be consistent, I must modify one or both of these standards by examining the reasons I have for accepting them and weighing these reasons to see which standard is more important and worth retaining and which is less important and in need of modification.
A more important kind of inconsistency is that which can emerge when we apply our moral standards to different situations. To be consistent, we must apply the same moral standards to one situation that we apply to another unless we can show that the two situations differ in relevant ways. I might believe, for example, that I have a right to buy a home in any neighborhood I wish, because I hold that people should be free to live wherever they choose. Yet, I am among the first to oppose the sale of the house next door to a group of mentally retarded persons. But what is the difference between the two situations that justifies this difference in treatment? What is the difference that makes it all right for me to buy a home in any neighborhood, but not them?
There is another sense in which the need for consistency enters into ethics. We might hold consistent moral standards and apply them in consistent ways, but we may fail to be consistent in who we are as individuals. We often use the word "integrity" to refer to people who act in ways that are consistent with their beliefs. Here consistency means that a person's actions are in harmony with his or her inner values. Polonius, a character in Shakespeare's Hamlet, points out--perhaps with some exaggeration--how critical such integrity is to the moral life when he says to his son, Laertes:
This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man.
Consistency in our lives also implies an inner integrity. It may be the case that a person's inner desires are allowed to conflict with each other. For example, a desire to be courageous or honest may be contradicted by a desire to avoid the inconvenience or pain that courage or honesty often requires. Allowing such a conflict is self-defeating because these desires are contradictory. To achieve consistency, we must work to shape our desires to produce a kind of internal harmony.
So central is consistency to ethics that some moralists have held that it is the whole of ethics. They have argued that if people consistently treat all human beings the same, they will always act ethically. Ethical behavior, they argue, is simply a matter of being consistent by extending to all persons the same respect and consideration that we claim for ourselves. The Bible itself seems to imply that ethics consists of nothing more than consistency with the words: "Do unto others as you would have them do unto you: this is the whole Law and the prophets." (Matt. 7:12) This biblical verse sometimes has been interpreted as meaning that all of morality can be summed up in the requirement to avoid contradictions between what one thinks is appropriate for others and what one thinks is appropriate for oneself.
But is consistency all there is to ethics? We may be perfectly consistent with respect to our moral principles and values, yet our principles may be incorrect and our values misplaced. We may even be consistent in treating others as we treat ourselves, but this kind of consistency would hardly be the mark of a moral life if we happen to treat ourselves poorly.
We might say that while consistency is surely not sufficient for ethics, it is at least necessary for ethics. Ethics requires that there be consistency among our moral standards and in how we apply these standards. Ethics also requires a consistency between our ethical standards and our actions, as well as among our inner desires. Finally, ethics requires that there be consistency between how we treat ourselves and how we treat others.