Faced with such a question, you might rely on that old fallback, the Ten Commandments. But then someone might ask you to name some of them, and if you are like the average person, you might be out of luck. Most of us cannot remember more than a few of the Ten Commandments. In addition, it's hard to sincerely claim that you follow the Ten Commandments when one commandment is to honor the Sabbath (something most Americans don't do), and three other commandments are prohibitions against coveting -- rules Americans routinely violate when they see someone's Facebook post and think: I wish I had a car like that or I wish I had a house like that or I wish I had a wife that hot.
On this page Kent M. Keith makes an admirable attempt to state a universal moral code. The moral principles he states are all good and commendable. The only problem is that Keith ends up stating twenty moral principles, which is twice as many as found in the original Ten Commandments. It may be a great thing to be very concise when formulating a moral code. The shorter the moral code, the more likely you will be to remember it when faced with a moral choice. But is there some way that a good moral code can be stated in a single concise sentence?
Perhaps the best example of a concise statement of morality is the Golden Rule, which was stated by Jesus as: “Do to others what you would want them to do to you.” This is a very good moral principle that has been stated in one form or another in many religious traditions. Basically the same principle was stated centuries earlier by Confucius, who stated, “Never impose on others what you would not choose for yourself.”
Although the Golden Rule is a very good rule, it may not give you a clear signal of what to do in morally relevant cases in which you are not directly acting on a person. For example, suppose you have a fast car that you want to try out on the highway, by driving really fast. Who exactly are the others you are doing unto in this case? It's not quite clear, so the Golden Rule gives you no clear signal in this case.
Let me suggest a one-line moral code. I don't claim that it is better than the Golden Rule, but at least my one-line moral code will be slightly more concise, consisting of only five words and only seven syllables. The one-line moral code I propose is below:
Don't harm, lie, or endanger.
It's remarkable how much is covered by these five words, which I'll refer to below as “the code.”
The code prohibits murder (that's covered under “don't harm.”)
The code prohibits assaulting someone (that's covered under “don't harm.”)
The code prohibits being so nasty to someone that it causes humiliation or serious mental harm (that's covered under “don't harm.”) It doesn't prohibit criticizing someone in a moderate way that is not harsh enough to cause harm (something that is often necessary).
The code prohibits doing something such as driving too fast or driving while intoxicated (that's covered under “don't... endanger.”)
The code prohibits vandalism and arson (that's covered under “don't harm,” which applies to both people and property).
The code does not directly prohibit adultery, but it indirectly pretty much rules out adultery by prohibiting lying (it's almost impossible to be much of an adulterer without lying), and the "don't...endanger" part may also rule out adultery, as adultery normally endangers the mental well-being of the spouse being cheated on.
The code does not prohibit safe premarital sex, but in light of the abundance of sexually transmitted diseases, the code does (in many or most cases) prohibit behavior such as casual unprotected sex with a stranger or multiple partners (that's covered by "don't...endanger.")
To a person who is conversant with global warming issues, the code does prohibit environmentally reckless or environmentally harmful behavior with a very high carbon footprint, as that seems to be covered by the “don't...endanger” part, which applies not just to other people but to our environment.
The code does not directly prohibit stealing, but as the code says “Don't harm,” it would seem to prohibit stealing from anyone who may be significantly harmed by the theft. So the code would seem to prohibit something such as stealing a car from a middle-class person (which would cause significant harm), but the code does not prohibit acts such as stealing a loaf of bread from a middle-class person, or stealing a car from a man who is so rich that he has five other cars (since neither thefts would cause significant harm). That doesn't seems like much of a deficiency, and it is debatable whether an absolute prohibition against theft makes sense in a world of outrageous and ever-growing economic inequality (for example, it is not obviously immoral for a starving child in Egypt to pass by a rich tourist in an outdoor cafe, and steal a pastry from his table).
The code does not prohibit you from being a bit sassy or irreverent to your parents, but the “don't harm” part at least prohibits you from being frequently obnoxious to them (as that presumably would cause mental harm to them). Moreover, the “don't ...endanger” part implies a duty for parents to look after their children with care (something even more important than children respecting parents).
I think for a mere seven syllables, this teensy-sized moral code has a very high “bang for the buck,” in the sense that it covers a lot of territory in a minimum of words.