You’re in a hurry as you approach the supermarket, you know exactly what you need, and you won’t be a minute. All the spots are taken, except that handicapped spot near the door, and in a flash of turpitude, you take it. “What’s the harm?” you say to yourself, “I’ll just be a minute.” Of course, immediate harm ensues, when the next person who enters to lot needs the space. So our first principle, rather aptly, is Do no harm. One down, three to go.

It turns out the first item on your list is chocolate covered almonds. Mmmm, you love them. And as you lean over the bin, scoop in hand, you realize you are alone in the aisle. Remember, you’re in some sort of moral holiday here, so you decide to sample. And as the taste explodes in your mouth, you remember this sermon, and with it the second principle: Pursue the common good. Laws against theft are in place to allow us to live together as a society—and provide a set of assumptions about how we will behave—as we pursue the common good.

Next, you’re at the cash, and the check-out person has give you too much change. It’s a simple enough mistake, “an error in your favour” like Monopoly, but this time you have a choice. The first thing to consider is ‘what would I do if the situation was reversed?’ If you were short-changed, would you say something? Of course you would! So the next principle is simple: Treat others as you wish to the be treated. We call it the “Golden Rule,” a principle that exists in some form in almost every religion and philosophy.

Being moral is hard work, so it’s time to head home. As you walk toward the door, you notice that the edge of the rubber mat is flipped over, creating a trip hazard. What do you do? In the strictest technical sense, it’s not your problem. Stores have liability insurance just for such situations. But what if your 90 year-old granny is two steps behind? You fix the mat. What if it’s your 90 year-old neighbour? You fix the mat. What if it’s someone you’ve never met?

This scenario includes elements of all the principles we have defined so far: pursue the common good (a society where people care for strangers); do no harm (a reasonable person will see that the mat is potentially harmful); and treat others as you wish to be treated (I wish the person before me fixed the mat before I nearly tripped). Using all of these principles together, we define our fourth principle as Develop a moral character.