I have lost count of the number of times I have walked into a business and heard a leader say some version of: "I shouldn't have to explain this. It's just common sense."
And every single time, I think the same thing: If it were common sense, you wouldn't be in this room with me right now.
Common sense is not common. It is the most expensive assumption you can make as a leader, because it costs you nothing to assume — and everything if you're wrong.
What Leaders Mean When They Say "Common Sense"
When a leader says something is "just common sense," what they almost always mean is one of these things:
- "This is something I have known for so long, I no longer remember learning it."
- "This is obvious to people who have done my job."
- "I don't want to take the time to explain it."
- "I'm frustrated that someone got it wrong, and I want to put the blame on them instead of on the lack of clarity."
None of those are the same as "this is universally understood." But because we use the phrase as a shortcut, we conflate them — and end up holding people accountable for knowledge they were never given.
The Real Cost of the Assumption
Here is what happens in a business where leaders rely on "common sense":
An employee makes a decision. The decision turns out to be wrong. The leader is frustrated. They say, "Why would you do that? That's just common sense." The employee, embarrassed, doesn't push back. They go quiet. The leader thinks the issue is fixed because the employee got the message.
Three weeks later, a different employee makes the same kind of decision. Different specifics, same underlying logic. The leader, now angrier, has the same conversation. Quietly, the team starts to notice that there is a category of decisions where the rules are not written down — but you can get blamed for getting them wrong.
What does the team do in response? They stop making decisions. They escalate everything. They wait for the leader to tell them what to do. The business slows down. The leader is now overwhelmed because every decision is on their desk. They start to feel like nobody on the team can think for themselves.
Of course nobody can think for themselves. The team has been trained, through repeated experience, that thinking for yourself is dangerous when the rules aren't written down.
If you have to keep saying "that's just common sense," what you actually have is an undocumented rule. Document it.
The Better Approach
The leaders who run the best businesses I have worked in have a different operating principle: If I have explained something more than twice, I write it down.
Not in a binder nobody reads. In a place where the team actually works — a shared playbook, a process document, a checklist taped above the desk where the work happens. Wherever it lives, the rule is the same: if it's important enough that I want people to get it right, it's important enough to write down.
This sounds like extra work. It is the opposite of extra work. The leaders who do this find that:
- They have to explain things one time instead of forty
- New hires are productive in weeks instead of months
- Decisions happen at the right level of the organization without being escalated
- Mistakes drop, because the rules are knowable
- When mistakes do happen, there's a clear path to fix the documentation rather than blame the person
What to Do This Week
If you are a leader and this article struck a nerve, here is a small experiment. For one week, every time you find yourself thinking "this is just common sense" — pause. Ask:
- Where would someone on my team look to find this written down?
- If the answer is "nowhere" — is that an accident, or have I just decided this rule is too obvious to put in writing?
- What would it cost me to spend ten minutes writing it down?
Most of the time, the answer is "ten minutes." And those ten minutes will save you, your team, and your business hundreds of hours of confusion, frustration, and re-work over the next year.
Common sense isn't common. The leaders who understand that build businesses that scale. The leaders who don't, end up trapped at the center of every decision — convinced that their team just doesn't think clearly, when the truth is that they were never given a way to.