A good story usually demands a strong plot, and a strong plot is advanced through the skillful use of conflict.

Conflict, of course, starts with characters who think and act in specific ways; their patterns of behavior set the contours of how conflicts begin, progress and resolve over the narrative arc of the story.

Five introductory points about ethical consistency:

1. At heart, ethics relates to the process by which people make value-laden choices. When there’s no choice, or no values at stake, then the question isn’t an ethical one. For example, personal preferences (e.g., “I like cashews more than brazil nuts”) aren’t a source of moral dispute.
2. People aren’t always consistent, but they do tend to naturally fall into one of the broad ethical paradigms. No one does the right thing all the time, and always for the exact same reason; characters like Galadedrid Damodred in The Wheel of Time simply do not exist in the real world, so their presence in literary worlds proves especially jarring. Likewise, no one does the wrong thing all the time.
3. When pressed, people can do the “right” thing for the “wrong” reason — with wrong merely suggesting a conformance to a different (i.e., non-dominant) moral paradigm.
4. When pressed further, people can act against their moral principles. It doesn’t happen often, however. People who frequently make bad moral choices are inadvertently telegraphing that their ethical framework isn’t as straightforward as they claim.
5. People rarely reset their default ethical worldview. Such a change can happen, but it’s not often enough in the real world to use it as a plot device. Usually these changes follow from significant trauma or long-running psychological stress.

The most common “broad moral paradigms” include:

• Egoism. In a nutshell: Egoists do what redounds to the greatest good for the self.
• Deontology. Duty-based ethics (i.e., Kantianism) suggests that the morally correct behavior is that which meets a generalizable duty or universal moral rule. For example, people can agree to the maxim that “It’s never okay to lie” and therefore we have a duty to avoid lying. We must do our duty, no matter the consequence.
• Consequentialism. Consequentialism subdivides into many different groups. Utilitarians, for example, divide into “act utilitarians” (actions are judged) and “rule utilitarians” (the rules surrounding the actions are judged). Regardless of their tribe, however, consequentialists generally agree that the morally correct behavior is that which generates the greatest good or the least suffering, for the greatest number of people. Duty isn’t usually a major consideration.
• Natural Law Theory. The natural law suggests that innate patterns in human nature — discoverable through study of universal human behavior — should govern. Popular in the Middle Ages, this approach isn’t as common anymore.
• Divine Command Theory. The morally correct behavior is that which is willed by the supreme supernatural being(s). In other words: Do what God says.
• Virtue Theory. The virtues rely on the development of character and follow from the ethical teachings of Aristotle. A virtue theorist balances various virtues (e.g., temperance, fortitude, bravery) to arrive at a recommended course of action. The vices (sloth, envy, etc.) should be eradicated to grow in character and thus in virtue. In a sense, the ethically correct behavior is that which the virtuous person undertakes.
• Care Ethics. A modern innovation, care ethics seeks to preserve the relationships among those affected by an ethically difficult situation. The outcome is sometimes less relevant than maintaining amity. A special consideration is extended to people disadvantaged by the dispute.

Important non-theories include:

• Contractarianism. The idea with contractarians is that our only moral duties are those we explicitly negotiate with others. However, this line of thinking is just a variant of selective deontology (as in, I only have a duty to those for whom I agree to incur a duty).
• Rights Theory. Someone who emphasis rights above all other considerations is just aping a form of deontology (i.e., giving pride-of-place to the maxim that “people ought to respect the rights of others”). Depending on the justification, it’s also a variant of rule utilitarianism.
• Honor Theory. Approaches that emphasize honor — you see it often in urban hip-hop culture that emphasizes respect — tend to loosely follow a care-ethics framework.
• Ethical Nihilism. If you believe that there’s no such thing as morality, or that ethics can’t be universally applicable, then you’re a nihilist. But at heart, you’re really an egoist because you’re suggesting that whatever you do is, ipso facto, morally justified.
• Hedonism. The whole “live and let live in peace and harmony, dude” mindset follows from a variant of consequentialism with a bit of egoist seasoning.
• The Lex Talionis. The idea of “an eye for an eye” is sometimes incorrectly assumed to be a function of the natural law. In fact, natural law focuses on traits universal among humans; it’s not a surrogate for survival-of-the-fittest fetishism.

A few other points warrant mention.

First, ethical paradigms don’t relate well to the DSM-V. For example, an ethicist might classify as a “super-enlightened egoist” someone diagnosed by a psychologist as a sociopath. Many assertions of mental illness along the lines of sociopathic personality disorder or borderline personality disorder can distill into a form of ethical egoism that the psychologist simply refuses to accept as being a legitimate moral worldview. There’s long been a tension between the ethicist and the psychologist.

Second, many people mix their metaphors. They’ll follow the duty-bound approach of a Kantian for most things, but resort to consequentialist thinking when they want a free pass that Kant won’t offer. Or they’ll follow their scripture in their personal life but follow a care-ethic approach in their professional life. Again, consistency isn’t common, nor is it necessarily a desirable trait. But to the degree that people are inconsistent, they’re often consistently inconsistent.

In practice, adherents of each of these schools might come (correctly! and legitimately!) to different conclusions given the same case study. Consider the following hypothetical:

Bob arrives at work at 8 a.m. He sees his co-worker, Sally, arrive at 9 a.m. — but he discovers that she wrote 8 a.m. on her timesheet. After a bit of peeking, he concludes that she’s been faking her time card for several months, bilking her employer out of hundreds of hours of wages. Bob considers what he should do with his knowledge of Sally’s behavior.

In this situation, people can legitimately arrive at different conclusions.

Sometimes people get confused and think that because different people can make different ethical decisions for different reasons, that therefore morality as a concept is unworkable. Untrue. The complex moral reasoning of most ordinary people resembles the Myers-Briggs Type Indicator: One or two paradigms are dominant, another one or two sometimes crop up, and others almost never make an appearance.

If your characters consistently behave as humans would behave in the real world, then not only are your characters more plausible, but the conflicts generated by their clashes are more powerful. Never underestimate the power of base moral conflict to drive tension and keep a plot advancing. When done well, these psychological studies drive powerful reader engagement and lead to more compelling stories.