Are mental models and first principles contradictory or complementary?

They are not contradictory at all; they are complementary and very closely related, like a set of tools in a toolbox, each with a different purpose.

Let me explain with a simple analogy:

Thinking frameworks are like "recipes."

Previous generations, or you yourself, have accumulated a lot of experience. To make Kung Pao Chicken, you should cut the ingredients this way, add the seasonings this way, and cook it at this heat. If you just follow the recipe, you can generally make a decent Kung Pao Chicken. This is highly efficient and allows you to quickly solve most "known" problems. In our daily lives and work, we spend most of our time using various "recipes" like "SWOT analysis," "SMART principles," and so on. These are useful thinking frameworks that help us get started quickly.

First principles are like "understanding the underlying cooking chemistry."

You no longer memorize recipes; instead, you think: At what temperature does protein denature? Under what conditions does sugar caramelize (Maillard reaction)? What flavors result from combining acids and bases? You break down a dish into its most fundamental "physical and chemical changes."

When you only know recipes (thinking frameworks), you can only make dishes that have recipes. But when you understand the underlying cooking chemistry (first principles), you can not only make any dish from a recipe, but you can also improve them, and even create entirely new, unprecedented dishes.

So, how do they complement each other?

1. Use "thinking frameworks" daily for efficient problem-solving: You can't analyze molecular structures from scratch every time you cook a dish; that would be too exhausting. Most of the time, using existing recipes (thinking frameworks) is the fastest and most reliable option. It helps you handle 95% of daily tasks.

2. When encountering bottlenecks and seeking innovation, use "first principles" for breakthroughs: When existing recipes can't produce the taste you desire, or you want to pioneer a completely new style, "recipes" become a constraint. At this point, you need to go back to basics and use first principles to think: "What taste do I truly want? To achieve this taste, what are the most fundamental elements and reactions required?"

Elon Musk building rockets is a classic example. At the time, the prevailing thinking framework was that "rockets are extremely expensive," which was an established conclusion. But Musk used first principles to think: "What materials are rockets made of? Aluminum alloy, titanium, copper, carbon fiber... How much do these materials cost individually on the market?" He broke down the cost to the level of basic raw materials and found that material costs accounted for only about 2% of the total rocket price. This led him to a revolutionary conclusion: the cost of rockets could be drastically reduced if they built them themselves.

To summarize:

• Thinking frameworks are "techniques" (术), efficient tools that help you see higher.
• First principles are "principles" (道), fundamental laws that help you see deeper.

A capable person has many useful "thinking frameworks" in their mind, ready to be called upon to solve problems; but when these frameworks are insufficient, or they want to do something different, they can switch to "first principles" mode at any time to find answers from the ground up.