The theory that being good is a simple property that is irreducible or indefinable interms of anything else.

It seems like you're asking about a philosophical theory, but you didn't specify a question. The theory you're referring to sounds like Moral Non-Naturalism, which posits that moral terms (like 'good', 'bad', 'right', 'wrong') refer to non-natural properties that cannot be reduced to any natural property or set of natural properties. This theory is often associated with G.E. Moore's "open question argument".

Here's a step-by-step breakdown:

1. Identify the theory: The theory is Moral Non-Naturalism.

It seems like you're referring to the concept of moral simplicity, which is a theory in meta-ethics. This theory suggests that goodness is a simple, irreducible property that cannot be defined in terms of other properties. Here's a step-by-step breakdown:

1. The theory you're referring to is a part of meta-ethics, which is a branch of philosophy that explores the nature and status of morality.

2. This particular theory is known as moral simplicity or ethical non-naturalism. It was most famously defended by philosopher G.E. Moore in his book Principia Ethica.

3. According to this theory, being good is a simple property. This means that it is a basic, fundamental property that cannot be broken down into other properties.

4. The theory also holds that goodness is irreducible, meaning it cannot be reduced to or defined in terms of other properties. For example, it cannot be defined as "that which brings about the most happiness" or "that which is commanded by God".

5. Finally, the theory asserts that goodness is indefinable. This does not mean that we cannot understand or recognize goodness, but rather that we cannot provide a definition of goodness in terms of other properties.

6. It's important to note that this theory is controversial and not universally accepted. Many philosophers argue that goodness can be defined