First principle thinking is a problem solving strategy where you break problems down into assumptions. Then build the solution back up from axioms considered to be true. At MIT, many problem and tests are designed to be solved this way, so students can arrive at a single right answer.

However, the real world is full of imperfect information, which makes it harder to apply first principle thinking. Information is always changing and there are often hidden variables that affect outcomes in unpredictable ways. For example, whenever people are involved, behavior can be hard to predict and reason about. Finally, you are likely operating in a situation where you have incomplete information.

I think applying the scientific method can be very useful here. This looks like:

1. Gather information
2. Form a hypothesis
3. Run an experiment
4. Draw conclusions
5. Repeat

Skills that are useful in this system include being observant, making moves quickly, and being flexible with making hypotheses. Very different from taking tests in college, where you can apply first principles thinking to arrive at the right answer.