-Moore thinks 'goodness' can't be defined, but he is still a cognitivist and realist (are truths about what is right and wrong)
-goodness is known intuitively; it is indefinable but self-evident
-Moore makes a comparison with the colour 'yellow'
--> we would struggle if we were asked to define what yellowness is, yet each of us knows and recognises the colour and is able to point to it. Similarly, goodness cannot be described but we can point to many examples that we 'just know' are good
-Moore argues 'good' is a simple idea
-like the concept of yellow, it can't be broken into parts or properties
-a complex idea might be something like a horse, where we could list the parts or break the idea down into components, for example legs, mane, ears, etc.
--> we can't list the parts of yellowness or goodness because they are simple ideas