In his book The Psychology of Science, psychologist Abraham Maslow introduces the concept that’s come to be known as Maslow’s hammer:

Imagine that an aspiring entrepreneur takes out a loan, starts a company, and goes bankrupt shortly afterward. She then falls into a depression and commits suicide. 

What happened? 

Your answer may depend on your area of expertise.

For example, if you’re a finance expert, you might question whether a loan was the right instrument. As a socialst, you might blame the tragedy on the failures of capitalism. 

If you’re a religious conservative, you might see the outcome as a punishment from God. And from the perspective of a psychiatrist, you would look at the entrepreneur’s mental health history.

Maslow’s hammer suggests that when you try to identify the source of some problem, you’re likely to view it through the lens of your expertise.

The problem is that this can lead to an over-reliance on familiar expertise or tools, even when better options are available.

For instance, imagine that you’re a manager with ten employees. 

If you use a one-size-fits-all approach to manage all of them, this could make you blind to potential problems and limit your team’s overall effectiveness.

Author Rolf Dobelli writes in his book The Art of the Good Life that the world is too complex for any one person to understand it: “Even if you’re highly educated, you can only understand a tiny part.”

But for Dobelli, that reality should be empowering, not discouraging. 

You can have outsized impact and success if you stay within your “circle of competence,” a term coined by the investor Warren Buffett.

Inside that circle are the skills you have mastered. The key is to know your circle of competence and stay within it. The size of your circle is less important than knowing its boundaries. 

A brilliant salesperson can solve the same problem in a fraction of the time that it would take a salesperson who is mediocre.

The same goes for computer programmers, designers, lawyers, researchers, surgeons, and other skills.

Another benefit of staying within your circle of competence is that you no longer need to feel bad about your deficiencies.

It doesn’t matter how many areas you’re average in. What matters is that you’re far above average in at least one area. A single outstanding skill is more valuable than a thousand mediocre ones.

As Dobelli puts it: “If your kids can’t tell whether that squiggle is supposed to be a horse or a cow, stop dreaming of a career as an artist. If you can barely cope with a visit from your aunt, drop the idea of owning your own restaurant.”

Both Maslow’s hammer and the circle of competence discussed above focus on how much an individual with a single area of expertise can or can’t do. 

But many of the most effective teams and organizations find ways to combine multiple types of expertise in productive ways.

Author and researcher Josh Kaufman writes in his book The Personal MBA that one way to view the benefits of complementary expertise is through the lens of comparative advantage, a concept from economics.

For example, if you want to build a house, it’s probably more efficient to hire a general contractor and specialists who regularly do the kind of work that the project requires. You could try it yourself, but unless you know what you’re doing, it will likely take longer and the results won’t be as good.

Comparative advantage is also an argument for diverse teams. If your team members have a variety of backgrounds and skills, then it increases the likelihood that one of them will know what to do in any given circumstance.

Conversely, if every team member has the same background or skills, it’s more likely that the team will make a preventable error or get stuck.

“… all the wisdom of the world is not to be found in one little academic department … You’ve got to have models across a fair array of disciplines.”

- Investor and Vice Chairman of Berkshire Hathaway Charlie Munger in his 1994 speech at the USC Marshall Business School