For months I’ve been puzzling over the question, sometimes until my head hurt. I’ve read books on the psychology of mistakes, journalistic mistakes, life-altering mistakes, history-changing mistakes. I’ve listened to stories people have told me about the mistakes they believe they’ve made, and for their courage and honesty I will be forever grateful.

Still, after all this, I don’t know if I’ve come any closer to understanding what a mistake really is.

The Oxford Dictionary defines a mistake as an act or judgement that is misguided or wrong. But I’ve found that everyone has a different idea of what constitutes a mistake.

Donald A. Norman, author of The Design of Everyday Things, makes a distinction between slips and mistakes. According to him, slips occur when we are fully aware of the correct action and intend to carry it out, but somewhere along the way we accidentally make an error. This is what happens in the case of typographical errors, for example. “Most everyday errors are slips,” writes Norman. “Intend to do one action, find yourself doing another.”

Mistakes, on the other hand, are errors that are the direct result of conscious, incorrect decisions. “Mistakes result from the choice of inappropriate goals. A person makes a poor decision, misclassifies a situation, or fails to take all the relevant factors into account.”

Another author, Bill Fawcett, starts by setting out the criterion he used to compile 100 Mistakes that Changed History. “To qualify as a mistake, the error has to be something that the person making it knew better or should have known better than to make. Being outwitted is not a mistake; doing something so stupid that any reasonable person would know it would cost you the battle, your kingdom, or your life is a mistake.”

While I found Fawcett’s book to be quite enlightening and informative as well as entertaining, I find his definition of a mistake rather murky. Does the mistake, then, lie in the outcome of an action? In other words, if something you did had a bad or unexpected outcome, could you claim that it was a mistake even if you knew better than to do it in the first place?

I had a lively discussion about this with a colleague of mine, who said emphatically, “It’s not about outcome, it’s about intent. Kissing a woman you thought was your wife, but turns out not to be your wife, is a mistake. Kissing a woman you know is not your wife is not a mistake.”

I agree that some things are clearly black and white, and substituting “I made a mistake” for “I did something wrong” is the weasel’s way out after being caught in the act: the adulterous spouse, the corrupt politician, the cheating athlete. “I made a terrible mistake,” said Canadian sprinter Ben Johnson in an interview 25 years after he had to give back his multiple Olympic medals because he was caught doping.

But what about those times when we try to do something good, only to have it backfire on us? Or those times when something we’ve done that we thought was harmless has consequences we never even imagined? Are these what we could call “honest” mistakes? And why do we have to qualify some mistakes as honest? Is there such a thing as a dishonest mistake?

My head is starting to hurt again.

***

Is it still a mistake if the unexpected outcome is a happy one? Someone told me this story: a man from the Ivory Coast left his fiancée to study in New York City. While he was gone, she had an affair. When the man came back and found her pregnant with the other guy’s child, he decided to marry her anyway, and to bring the child up as his own. Many people likely thought it was a mistake on his part, that it was far more than she deserved. But he did it anyway, and eventually took his wife and her baby girl to live with him in New York City.

On September 11, 2001, that baby girl—now school age—felt sick, and her father decided to stay home with her. So it happened that he did not go to work in his office at the World Trade Centre that day. His “mistake” ended up saving his life.

***

Mistakes can also change the outcome of a person’s life by changing his or her character. One woman told me she regretted not standing up to her bossy older sister when she was younger, especially after one particular incident which left her doubtful of herself and her ability to make her own decisions.

One thing that most people do seem to agree on is that mistakes are valuable—even necessary—for personal growth.

“Mistakes had to be made for me to see that I wasn’t untouchable. That I wasn’t invincible,” said one woman.

Out of all the people I talked to, only one said she thinks the adage “learn from your mistakes” is a trite dismissal of somebody else’s personal, painful, and perhaps damaging experience. “Sometimes it’s not so easy to see what you could possibly learn from all that mess,” she says ruefully.

***

I suppose that in the end, a mistake is something that you think will bring you joy but instead brings you pain. Sometimes we bring it on ourselves; other times we are the unwitting cause of events that unfold beyond our control.

But whether we are culpable or not, and whether the mistake is big or small, I think that if you wait long enough, it can bring you something else, one more thing you didn’t expect or foresee—not pain, not joy, but a lens that allows you to view both pain and joy in unexpected ways.

“Sometimes I feel like my life is just one big mistake on top of another,” said one woman, musing on her marriage. “And then I look to my side and I see this little imp of a monster lying next to me and somehow the mistakes seem less….less grave, less tragic, less of a mistake, because something beautiful came of it.”