When should you use first principles thinking? When should you avoid it?

“First principles thinking”is a fairly popular phrase out here in the Bay – and for good reason: it’s a powerful mental tool.

Many of the most effective people I work with are exceptional first principal thinkers.

It’s also an area of growth for me. See below for some reflections on the idea.

What is first principals thinking?

The best description I’ve heard is that is it reasoning by root cause rather than reasoning by analogy.

Instead of trying to figure out how something is like another thing, it is more about keeping on asking “why” about the specifics of one thing.

For example, if I were trying to build a cheap rocket to get to Mars, I could look at the price reduction trajectories of other similar complex machines, or I could do a part by part analysis of each component of a rocket.

The first is reasoning by analogy, the second is reasoning through the specific issue at hand.

Yes, Elon Musk is a major proponent of first principles thinking.

Why is first principles thinking useful?

Thinking by analogy is useful in that it is efficient: it quickly allows us to make guesses about unfamiliar issues by comparing them to familiar issues.

However, thinking by analogy is also noisy: the things you are comparing – especially in the case of really hard problems – will never be truly the same. So you are inevitably losing information by making erroneous implicit assumptions.

Ideally, first principles thinking will increase the amount of accurate information at hand, which will help with sound decision making.

Why is first principles thinking dangerous? 

It takes a lot more mental energy to think down to the root causes of every issue you face.

Moreover, the ability to execute sound first principles thinking will most likely require some subject matter expertise. While it’s possible to get to root causes without being a content expert (this is what junior strategy consultants often attempt to do), I’m skeptical that you consistently identify all root causes without deeply understanding the content.

Often times, I catch people who pride themselves in first principles thinking making major mistakes. This is especially true when they are talking to me about education, which happens to be something I know a lot about.

The world is an ever complicated place, and if you don’t have a handle on research and a broad set of real life facts, you can end up with high confidence in first principles that aren’t anchored in reality.

When should you use first principles thinking?

My hunch is that using first principles thinking is most useful in areas where: (1) you have subject matter expertise (2) you have time to devote to thinking about the issue (3) you have external feedback mechanisms that will tell you if you’re right.

I think reasoning by analogy and / or trusting experts / or simply not having an opinion (an under used option!!!!) is best in situations where you don’t have the requisite expertise, time, or feedback mechanisms to conduct first principles thinking.

How can you getter better at first principles thinking?

I’ve been thinking about this a lot lately; here’s some suggestions:

1. Get into friendly arguments with people who are good first principle thinkers and watch them work through issues. I have 3-4 great first principle thinkers in my life and I’ve learned a ton from watching them think. If you don’t have them in your life, listen to podcasts and read blog posts by people who excel at first principles thinking.

2. Use thinking devices such as getting to root causes by asking “why” 5+ times before you settle on viewing something as causal or true.

3. Cultivate anxiety about not being a good first principal thinker. Whenever I’m confronting a thorny issue in education, I always pressure / chastise myself to take the time to do first principles thinking before voicing an opinion.

Good luck.

3 thoughts on “When should you use first principles thinking? When should you avoid it?

  1. Pingback: A Place for Questions | From guestwriters

  2. Ron Gubitz

    Areas in which one has expertise, for the average person, is likely to be a rather small number of subjects, right? Based on time constraints, or the likelihood that expertise is developed over “10,000” hours of deliberate practice, for most folks this will mean the field in which they work, or maybe what they major in college, only.

    There is no way I can rigorously use first thinking principles when looking at different candidates platforms… Or ballot initiatives. The “no opinion” option might lead me to NOT vote, or to then use analogy reasoning. Investing would be another place I could see the desire to be a rgorous first principle thinker clash with the limits of my time. And trusting experts for these things seems difficult or risky.

    So, about how many subjects, on average, do you use this thinking for?

  3. Ken Bubp

    Definitely a useful frame.

    Some limitations, from this link (http://www.qualitydigest.com/inside/fda-compliance-news/root-cause-analysis-addressing-some-limitations-5-whys.html#), esp. to 5 whys. #2 resonates particularly. Other first principles approaches may be able to mitigate #2.

    “While many companies have successfully used the 5 Whys, the method has some inherent limitations. First, using 5 Whys doesn’t always lead to root cause identification when the cause is unknown. That is, if the cause is unknown to the person doing the problem solving, using 5 Whys may not lead to any meaningful answers. Second, an assumption underlying 5 Whys is that each presenting symptom has only one sufficient cause. This is not always the case and a 5 Whys analysis may not reveal jointly sufficient causes that explain a symptom. Third, the success of 5 Whys is to some degree contingent upon the skill with which the method is applied; if even one Why has a bad or meaningless answer, the whole procedure can be thrown off. Finally, the method isn’t necessarily repeatable; three different people applying 5 Whys to the same problem may come up with three totally different answers.”


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