Question: “If Buddhism teaches that there is no real self or individual identity (anatta, anatman), then how would Buddhism classify thoughts, emotions, opinions, etc.? If I have no real self, then what is the source/origin of (fleeting) happiness or my preference for the color red? Are they arising out of nothing?”
There are 8 consciousnesses in Buddhism. The first 5 are our senses (eyes, ears, nose, tongue, touch). The 6th consciousness is our mind. The 7th is the combination of the first 6, it is our habits. It’s the 7th consciousness where our thoughts, emotions, opinions, judgements, biases, etc. come from. These are the conditions that our life’s causes have created. It is here where our karma is created and moves from life to life in our 8th consciousness. Our 8th consciousness, the alaya consciousness, is what we can call our “self.” It’s the only one that really matters.
So as we think, say and do and we create our opinions, develop our personality, create judgements, etc. we are creating the karma that stores in our alaya consciousness and in there those karma seeds are planted and depending on the conditions, they will either be positive, negative or neutral.
Nothing arises from nothing. There is always a source to something. From your example, the only reason we see the color red as “red” is because we have put a name to this phenomena and called it red, so we know this color as red. But is it really red, or is it red because we call it red? We might call it or see it as red, but someone else might call and see it as orange – so is it red or orange? Whose right and whose wrong? Our own perceptions and opinions about things arise from what we know and can perceive from our first 6 consciousnesses.
Until we can see things as they really are, we will always see them as the phenomena we’ve given them. For example, the computer or smartphone we’re using to read this. If we take it apart, at what point does it seize to be a computer or smartphone? When it stops working or when it’s out into a thousand pieces? It’s a subjective judgement. But the point is, that “computer” is a designation we give to a phenomena; there is no inherent “computer nature” dwelling in the computer!
There is a famous Indian monk named Nagarjuna that said it is incorrect to say that things exist, but it is also incorrect to say that things don’t exist. Because all phenomena exist interdependently and are void of self-essence, and all distinctions we make between this and that phenomena are relative. So things and beings “exist” only in a relative way.
Smile and be well!