This post originally appeared on The Thinker on August 9, 2007.

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One time many years ago, when I was a junior-level engineer, I was drawn into an argument with a very senior technical guru. This individual was a true “alpha geek”, a geek among geeks. He had a PhD and was widely regarded as an expert in his technical discipline, with a long list of accomplishments and publications to his name. From a standpoint of pure analytical capabilities, he was also one of the smartest people I had ever met.

I can’t remember exactly what we argued about, but I remember the nature of the argument quite well. It went like this: First, he would assert a specific point. Next, I would respond, either by agreeing with him, or by countering his argument with a point of my own. Then he would present his next point. And so on… lather, rinse, repeat. But his next point frequently had no connection whatsoever to what I had just said, as if he had been too busy choosing his next words to even listen to mine. And to the extent that he did hear me, he became increasingly incensed and defensive as I took issue with his assertions. Ultimately he melted down completely and resorted to outright insults, at which point everyone in the room knew that I had pretty much won the argument – or, more accurately, that he had lost the argument himself by stooping to abusive remarks. (Except him; he went away thinking he had “put me in my place.”)

Further interaction with this particular individual over the years only confirmed what I had then begun to suspect. He was so emotionally attached to his opinions that he viewed any disagreement as an attack against him personally. Moreover, he was so closed-minded to other points of view – so convinced that he was right and everyone else wrong – that he regarded debate as a one-way transfer of knowledge from him to others, to bring their opinions into correct alignment with his own. He was truly uninterested in what anybody else had to say. To him debate was a process of defending and dispensing, rather than improving upon, his opinions.

This brings me to the most fundamental tenet of critical thinking:

Be committed, first and foremost, to getting at the truth.

As a critical thinker, the truth is what you really care about. Your opinions are just instantaneous approximations of the truth — approximations which you constantly seek to improve upon. To be a good critical thinker you must hold your own opinions at arm’s length, only tentatively subscribing to them and only in proportion to what can be justified by evidence and sound reasoning. You should regard debate not as the defense of your opinions or as a struggle to win others over to your way of thinking, but rather as an opportunity to gain new evidence and alternative perspectives. If the new evidence is consistent with a tentative opinion, then that opinion can become a little more firm, a little less tentative; otherwise, you revise your opinion, thereby moving it closer to the truth.

To reinforce this point, I hereby offer my dumb analogy of the day:

Critical thinkers should live in tents, not in castles.

People who are opinionated and closed minded (sometimes euphemistically characterized as being “strong in their convictions”) live in castles. Interested only in the defense of their opinions, they throw up walls and embattlements from which to protect and defend their firmly entrenched beliefs against attack. Castles by their very nature, while good for defense, are set in stone and cannot move, which is just fine with the opinionated person.

In contrast, good critical thinkers live in tents. Interested only in moving their opinions as close to the truth as possible, they must be able to pull up stakes and relocate as new arguments and new evidence cause them to reconsider their opinions. Tents by their very nature are not defensible, but that’s fine. The critical thinker doesn’t regard a criticism or disagreement as an attack to be defended against, but rather as a helpful tip that suggests a better campsite just over the next hill.

My opening story about the technical guru also brings up an interesting point having to do with intelligence and critical thinking. The fact that somebody so analytically brilliant could possess such dysfunctional thinking skills demonstrates that even geniuses are susceptible to the various cognitive biases and human weaknesses that can corrupt our thought processes. This brings me to a second major point I would like to assert about critical thinking. I am not 100% convinced that I am correct (see? I’m holding my opinions at arm’s length!), and would welcome any debate on this point, but I hereby assert that:

Practical intelligence is determined more by critical thinking skills than by IQ.

By “practical intelligence”, I mean a person’s intelligence for all practical purposes – i.e., how well a person can come to the right opinions, make the best decisions, and formulate good solutions to problems in the real world. In contrast, IQ is a measure of how well somebody performs purely analytical tasks in a non-real world environment, such as working out logic problems on an IQ test. IQ is definitely a predictor of success in life (for example, see this Scientific American article). And we might reasonably expect smarter people to be more prone to adapt good critical thinking skills. (However, intelligent people are more susceptible to certain thinking biases.) But I claim it is really the critical thinking skills, and not the IQ itself, that is the success factor.

That IQ itself is not as important as critical thinking, in terms of determining a person’s “practical intelligence”, is good news for everyone. IQ is an inherent trait that learning and training cannot change by more than just a few points. You are pretty much born with your IQ, and only a small percentage of us are born geniuses. But critical thinking is a set of skills and attitudes that can be learned and practiced by anyone. By improving your critical thinking abilities you can increase your “practical intelligence”.

So if you’re still living in a castle, your first step to improve your critical thinking abilities is to put that castle on the market and start shopping for a good tent.