Deontology is an ethical theory that uses rules to distinguish right from wrong. Deontology is often associated with philosopher Immanuel Kant. Kant believed that ethical actions follow universal moral laws, such as “Don’t lie.  Don’t steal.  Don’t cheat.”

Deontology is simple to apply. It just requires that people follow the rules and do their duty. This approach tends to fit well with our natural intuition about what is or isn’t ethical.

Unlike consequentialism, which judges actions by their results, deontology doesn’t require weighing the costs and benefits of a situation. This avoids subjectivity and uncertainty because you only have to follow set rules.

Despite its strengths, rigidly following deontology can produce results that many people find unacceptable. For example, suppose you’re a software engineer and learn that a nuclear missile is about to launch that might start a war. You can hack the network and cancel the launch, but it’s against your professional code of ethics to break into any software system without permission. And, it’s a form of lying and cheating. Deontology advises not to violate this rule. However, in letting the missile launch, thousands of people will die.

So, following the rules makes deontology easy to apply. But it also means disregarding the possible consequences of our actions when determining what is right and what is wrong.