This post also makes a general point about ethics and moral philosophy, that they're really good for coming up with general rules and prohibitions which apply in most cases, but there are always exceptions to those "do shall nots." Ethical systems are great for helping you frame moral issues (which is how ethics is normally taught in the classroom), but in the end, judgment is essential for arriving at a final answer. And you can't teach judgment—you develop it over time.

Let's say Christine tells her best friend Sally that she's thinking of cheating on her husband. What would Sally say? Well, she might ask her friend why she's thinking of cheating. Did her husband cheat? Is he mean, cold, or distant to her? Has the romance left their marriage? All of these may—or may not—seem like relevant questions, even if in the end Sally says that cheating is wrong.

What would philosophers have to offer on the subject of cheating? I mean, listen to Sally—cheating is just plain wrong, isn't it? And our intuitions are definitely that cheating is wrong. Well, so is lying, but we can all think of situations in which we would lie, and we would justify it if asked. Even taking a life can be justified if done in self-defense, or to save another life. In philosophical theories of morality, there are few absolutes, which means no easy answers—but we do get to ask lots of good questions!

So what supports our intuitions that cheating is wrong? There are three obvious answers, which conveniently correspond to the three ethical schools we'll look at to answer the question.

Answer 1: Because it hurts your spouse

How would you feel if your spouse cheated on you? Some of you may know this from experience, but I think we can all imagine it—it hurts! You've been betrayed and lied to, and you feel angry, depressed, unworthy, second-rate, unwanted. You want to lash out at the same time you want to crawl inside yourself and hide. Your spouse chose to seek out intimacy of one sort or another with another person-not you. That defines "sucks."

Sorry if I hit a nerve—believe me, that wasn't my intention. But I wanted to make the point that infidelity is very hurtful, and does real psychological, emotional, and spiritual damage to one's partner. And to philosophers who teach an ethical system known as utilitarianism, hurting people is wrong, period.

Utilitarians maintain that the morality of an action depends on the amount of utility it creates, which can be thought of (as seminal utilitarian Jeremy Bentham did) in terms of pleasure and pain (among other concepts). One action is morally better than another if it leads to a greater amount of pleasure (or lesser amount of pain), and the right action is the one that leads to the greatest amount of pleasure (compared to pain). Utilitarianism is based on a lot of common sense, but can be absurdly demanding as well—for instance, if the poor would benefit more from a dollar than you, extreme utilitarians (such as Peter Singer) may demand that you give all of your money away to the poor until you are equally poor. But more moderate utilitarians would say that, given a choice among reasonable options, you must simply choose the one that, as far as you can tell, benefits the most people to the greatest degree.

Well, we already established that cheating hurts your spouse—that would seem to make it wrong to a utilitarian, at least prima facie ("at first glance"). Compared to remaining faithful, cheating lessens your spouse's happiness or pleasure and increases her pain. Of course, your spouse may not be the only one affected—your children may also be hurt, either if they find out and are vicariously hurt through Mommy or Daddy being hurt, or even if they don't find out and and your spouse's pain nonetheless flows over to them. Family members, close friends, co-workers—anyone who is close to you may be affected, and utilitarianism demands that every person count equally when figuring the total good and bad caused by an action.

However, guess who else counts in that "everyone"? You. And therein lies one reason utilitarians might allow for cheating in some circumstances, particularly cases in which there is good reason to believe that you will benefit from the affair more than others will suffer. Let's say the romance in your marriage has completely disappeared; you and your spouse no longer speak, touch, or connect in any way. You begin to look elsewhere for the affection and intimacy you crave, whether sexual, romantic, or both. Maybe you don't think your spouse would even care—he doesn't want to be with you anymore, so why should he care if someone else does? It might lift you out of your misery to have someone in your life that cares, that wants you around, that you mean something to, and vice versa.

In such a case, and assuming that no one else (children, friends, etc.) would be significantly affected, a utilitarian would probably say "go ahead, do it!" Utilitarianism allows for some people to get hurt, as long as some other people are benefited by a greater amount (which is a frequent criticism of utilitarianism). Of course, you could be wrong about your spouse's feelings, or even about how much you stand to gain from an affair (maybe your guilt would overwhelm any positive feelings). But if to the best of your knowledge (and without rationalizing it to yourself), you believe that cheating on your spouse would increase your happiness more than it would lower your spouse's (and that of anyone connected to you), then the utilitarian would have to allow it.

To make matters more ambiguous, there is another person who stands to gain from the affair—your paramour. She's a person, and her well-being must be included in your pleasure/pain calculations. So that's another "positive" to add to your own, possibly able to offset the harm to your spouse (and others). If the person you plan to cheat with is in a similar situation to yours—you're both abjectly miserable in your separate relationships—that would make the case for cheating even stronger. But then again, what about your paramour's significant other? That's probably a negative... oh, my head hurts! There's a lot to consider when making utilitarian decisions, and that leads to the criticism that utilitarianism puts too much of a burden on decision-makers.

Some people justify their affairs by saying "it's for the good of the marriage," or "it will make our marriage stronger." In other words, I may be hurting my spouse now, but in the long run, we'll both be happier. While this may actually be a rationalization when people say it, it does have some philosophical validity. Utilitarians don't simply compare the pleasure and pain that an action causes right now, but also the effects it creates in the future. Utilitarians use this thinking to defend or criticize policies on such things as governmental budget deficits or environmental impact that will affect not only people presently living, but their children and grandchildren as well.