Why do some people consider "first principles" just another term for "deconstruction"?

Ah, that's a very good question, and many people think that way. I can understand why, because "deconstruction" is indeed the most obvious and initial step in first principles thinking.

You can think of it this way:

"Deconstruction" is like taking a hamburger apart layer by layer and saying, "Oh, it's made of two buns, a patty, a piece of lettuce, a slice of cheese, and some sauce." You've analyzed its components, and that's where it ends. It's just an act of analysis.

But first principles thinking goes beyond that. After deconstruction, it continues to ask a series of more fundamental questions:

• Why do I eat this thing? — To get energy and enjoy the taste.
• Do energy and taste necessarily require the "bun + patty" format? — Not necessarily.
• What are the basic elements that constitute energy and taste? — Carbohydrates, proteins, fats, fiber, and various flavor molecules.
• Can I combine these basic elements in other healthier, cheaper, or more convenient ways to achieve the same goal of "getting energy and enjoying the taste"?

You see, after "deconstructing" the hamburger, first principles thinking doesn't focus on how to put it back together. Instead, it considers whether it can discard the fixed concept of a "hamburger" and, starting from the most basic "nutrition and flavor," create an entirely new food. Perhaps you end up inventing a nutritional paste or a liquid meal replacement.

So, to put it plainly:

• "Deconstruction" is merely taking existing things apart to see their components. Its endpoint is "I know what it's made of."
• First principles thinking is breaking things down to the most basic, irreducible fundamental truths (like laws of physics, or fundamental human needs), and then, starting from these basic truths, re-deriving an entirely new, potentially better solution. Its focus is on "creation," not just "analysis."

Therefore, to consider it just another way of saying "deconstruction" is to only see the first step, while overlooking the more crucial "reconstruction" process from scratch.