@xkcdbot Quite good. Doctors (in medicine) should be able to draw your cartoon with the eyes shut before they are allowed to practice.

I also encountered two real “scientists” in physics during my studies who did a similar, terrible mistake (one teaching physics, the other working in a lab on statistical physics and thermal transfer). The model they developed led to a differential equation. We didn't have the tools to solve this equation. Then they said:

Here is a solution to the equation; since reality shows only one behavior, this is necessarily the solution.

And I thought: “Oh yeah, and what if your model is simply missing elements that explain how reality selects its particular solution?”