Our lives are full of facts that we have to presume true. If we tried to verify every single truth, we would end up paralyzed, constantly checking and re-checking everything, like a mental patient with a debilitating case of OCD.
Certainty is a spectrum
Certainty is a spectrum, and knowing where a given fact falls on the spectrum is the difference between good assumptions and bad assumptions.
When I walk, I assume that the ground that I am going to step on will not collapse. If I had to verify that fact, I would not be able to walk and I would spend my life sitting on a chair or testing the floor in front of me.
When I lock a car door using a remote control, the car makes a brief loud sound to announce it did what I think I asked. When I hear that sound, I can confidently assume that the door is locked. Most of us do not need to verify that fact trying to pull on the handle. However, some people with OCD keep on questioning their observations and feel the need to verify that kind of thing anyway. They might also not trust their verification and might continue re-locking and re-testing the door several times before being satisfied. This can be a debilitating problem that most of us normally solve making assumptions.
On the opposite end of the spectrum, I could cross a city street without looking left and right, assuming that there are no cars on the road. Most of us would consider that dangerous, for good reasons.
The philosopher Mr. Eugene Lewis Fordsworthe is credited with crafting the phrase “assumption is the mother of all mistakes.” While assumptions are part of life, I have used this expression often over the years, and I believe in its wisdom when applied to high-stakes situations. When I quote it, I add “evil” to more clearly describe my feelings about it.
Assumptions do Not Always Lead to Mistakes, but Most Mistakes are Caused by Assumptions
As mentioned, making assumptions is not always a bad thing, as it lets you move quickly and freely when you can’t acquire or verify all the information. This might seem to be a contradiction to the principle, but it is not. The principle says that when a mistake is made, you can most likely find a bad assumption behind it. However, the principle does not imply that all assumptions lead to mistakes.
I have worked with many individuals that refuse to make a call without all the information. Their rationale is that they do not want to make assumptions, even if they know they will never have all the data. This behavior leads to analysis-paralysis, which is often worse than making a mistake. As a matter of fact, the worst decision is no decision at all. The desire to find more information before making a call is healthy until you reach a point of diminishing returns. When supporting additional knowledge becomes too expensive to collect, making a decision without it is essential.
Assumptions are Risk Factors
The key reason behind the “assumption is the evil mother of all mistakes” principle is to shine a direct light on areas of risk. When you know you are stating something as true without verified evidence, you should be aware that you are taking a risk. Whenever possible, it is crucial to validate the rigor of any supposition, but it won’t always be possible or practical.
Making a List and Checking it Twice
When you are making a complex high-stakes decision, you need to ask what truths are being assumed, and you need to question them. To aid the process, I recommend making an assumption-list and identify the reasons why you think every item in the list is an acceptable risk. Then, check that the items are consistent with each other and that they are not contradicting known factual information. Finally, jot down how you would know if some assumptions in this list were wrong, and what potential action you could take in that case.
Having such a list is going to be useful later in case you make a mistake, as it is the first place to look for possible causes.
How to Apply the Principle
In high-stakes situations, let the principle remind you to list, discuss, verify (when possible) and document (when necessary) the assumptions that are being made. Never assume that no assumptions are being made. That would be the first mistake to confirm the principle. The question is not IF there are assumptions being made, the question is what they are, and what are the consequences if they are wrong.
Finally, do not let risk stop you from making a call. I am not suggesting that you need to avoid taking risks. Taking risks is good. I am suggesting that you need to take risks deliberately, not accidentally.