What ethical challenges might it encounter?

Let's put it this way: applying "first principles" to building rockets or electric vehicles is incredibly powerful because it deals with problems in the physical world, where there are standard answers. But applying it to ethics, that is, the question of "how should humans act correctly?", becomes much more complicated. There are several major pitfalls:

1. The inability to find that "first" "axiom"

In physics, first principles start with universally accepted and repeatedly verifiable axioms like "the speed of light is constant" or "energy is conserved." But in ethics, what is that fundamental axiom?

• Is it "the greatest happiness for the greatest number" (utilitarianism)? Then, to ensure the happiness of five people, is it acceptable to sacrifice one innocent person?
• Is it "never lie" (deontology)? Then, when facing a murderer pursuing your friend, should you still tell the truth?
• Is it "just do what's best for yourself" (egoism)? Wouldn't society descend into chaos?
• Is it "what God/Heaven says is right"? But who can prove what God truly said, and how do you convince non-believers?

As you can see, the starting point of ethics itself is a matter of "belief." People have been arguing about what the foundation even looks like for thousands of years. You can't build upwards from a universally accepted starting point like stacking building blocks. This is the most critical difficulty.

2. Humans are not purely rational machines

First principles are a very "cool" thinking tool: calm, rational, and unemotional. But ethics and morality are precisely "hot"; they are deeply rooted in human emotion, empathy, intuition, and cultural traditions.

A classic example: Imagine you're standing on a footbridge, seeing an out-of-control trolley about to hit five people. Next to you is a large man; if you push him onto the tracks, he could stop the trolley and save those five people.

From a purely "first principles" perspective (e.g., utilitarianism: five lives > one life), pushing him would be the "correct" action. But almost every normal person's first reaction is: "That's horrible, I couldn't do it!" This feeling of "not being able to do it" is emotion and intuition at play. If ethical problems completely disregard human emotion, the conclusions drawn often become anti-human.

3. The real world is too complex, with too many variables

First principles thinking likes to simplify problems down to their core elements. But human society is an extremely complex system. A seemingly simple moral decision might involve countless variables such as culture, history, personal relationships, and power structures.

For instance, the principle "debts must be paid" sounds very basic, right? But what if the debtor is a starving pauper, and the creditor is a billionaire for whom the money is negligible, while for the pauper, it's a matter of life and death? In this situation, is the simple principle "debts must be paid" still so self-evident?

Trying to apply a simple, universal principle to an endless, special-case-filled reality often leads to hitting a wall.

In summary:

Applying first principles to ethics is like trying to open a lock made of human hearts with a key of mathematical formulas.

It's not entirely useless; it can help us break free from the mindset of "everyone does it, so I'll do it too" and reflect on whether our ingrained moral concepts are truly reasonable.

However, its biggest difficulty lies in this: the ethical world has no universally accepted "physical laws"; it is full of emotional warmth and complex human relationships. Attempting to guide all human behavior with one purely rational, single fundamental principle will either lead to endless debate or result in some truly terrible conclusions.