A few days ago, CNN reported the firing of an animal shelter employee who had mistakenly euthanized Target, a dog who saved U.S. soldiers in Afghanistan from a suicide bomber. The employee was accused of not following procedures correctly. The name of that employee was not mentioned in the news report because--not unexpectedly--many threats had been made against them.

It is easy to assume that with diligence, a human being can avoid making errors. What naturally follows from that assumption is the belief that any error a person makes must represent a moral failure on his or her part. When someone makes an error that has grave consequences, as in this case, we can be especially harsh in our judgments of their action.

However, cognitive scientists have learned that this assumption is not accurate. Human beings cannot completely avoid making errors, because the mind by virtual of the way it operates is error-prone. Research done during the last few decades has revealed the kinds of errors most commonly made, the circumstances that can make errors more likely (e.g., a procedure that's confusing in some way for a person trying to follow it), even the differences between errors commonly made by experts vs. novices.

Professor James Reason's taxonomy of human errors, which I encountered in grad school, drove home these points for me, because it was so easy to see that I commonly make many of the errors described in his detailed taxonomy. Take, for example, the category of unintentional actions, which includes actions that don't proceed as planned. This category includes two main types of errors: slips and lapses. You make a slip when you pour cereal into your breakfast bowl, then absent-mindedly pour coffee onto the cereal instead of milk. I certainly do this now and then. You make a lapse when you set your briefcase or backpack by the door so you won't forget it, but then leave without it (I made this error last week).

Professor Reason includes a wide variety of other types of errors in his taxonomy, which is laid out in his book, "Human Error."

I don't know any of the details about what went wrong in the animal shelter, nor should I. I don't think that the fact that we necessarily make errors absolves us of all responsibility for our actions, because we know from experience that we can make fewer errors by being more careful. But it seems to me that Professor Reason's taxonomy should suggest to us that cutting each other slack, especially when all the facts aren't available to us, is a wise approach.