Over the last decade, the concept of first-principles thinking has taken off like wildfire among the startup founder community. The idea, popularized by Elon Musk, comes from the world of physics, where it refers to “fundamental assumptions that cannot be reduced further.” The core principle is that you should never do things just because people say, “That’s how it’s always done.” Instead, you derive your truths from first principles so you can verify for yourself what is true and what is not. This approach aims to eliminate as many errors as possible and to surface inefficiencies and fallacies that others might miss when they simply accept conventional wisdom without questioning it.
This idea, like most ideas that capture the zeitgeist, sounds phenomenal in theory. However, like any other principle, it comes with tradeoffs that often go undiscussed. Especially in the founder community, ideas like first-principles thinking are popularized because founding a startup can resemble gambling—you attach yourself to the stories of the 1% who succeed and overlook the 99% who fail. You convince yourself that if you can just mimic the 1% perfectly, you’ll succeed as well. In reality, the truth can be very different. Successful founders often preach the inefficient, low-probability, high-risk angle because it worked for them. It’s reminiscent of the xkcd comic about the lottery winner who attributes their win to a specific “strategy,” ignoring the sheer luck involved.
Anyway, to make this more concrete, the often-overlooked downside of first-principles thinking is that, without exceptional intuition, it can become a huge time sink rather than a path to discovering missed inefficiencies or fallacies.
Let me paint a picture of a recent experience in my engineering job that exemplifies this. I’ll abstract out some details to keep the focus on the main point. When I took on my first project at my current company, several colleagues advised me to use Approach A for implementing a particular change. When I asked for the reasoning, no one provided a clear explanation; they just repeated that everyone says it’s easier. Coming off my time as a founder, I put on my first-principles thinking hat and decided to go against the grain with Approach B. From a purely logical standpoint, Approach B left less room for error and was, in my view, a cleaner implementation.
Fast forward two and a half weeks, and I discovered the hard way that I should have followed everyone’s advice. The dependencies within our company’s ecosystem—most of them undocumented and communicated through tribal knowledge—made implementing Approach B an extremely painful and tedious process. Had I gone with the recommended method, it likely would have taken under a week. That’s an extra week and a half of productivity I could have spent on more impactful projects.
As a side note, I do realize there’s another angle to this argument: when you learn things for yourself through first-principles thinking, you can gain deeper insights. However, that leads to a more philosophical debate about whether the learning benefits outweigh potential inefficiencies. My goal here is simply to point out that first-principles thinking does have a downside: it can be time-consuming and risky. You might still decide to apply it to every decision, but it’s crucial to acknowledge the tradeoffs and proceed with both eyes open.