Think of what happens when you put a new food into your mouth. You don’t have to decide if it’s disgusting. You just know. You don’t have to decide if a landscape is beautiful. You just know.
Moral judgments are like that. They are rapid intuitive decisions and involve the emotion-processing parts of the brain. Most of us make snap moral judgments about what feels fair or not, or what feels good or not. We start doing this when we are babies, before we have language. And even as adults, we often can’t explain to ourselves why something feels wrong.