Ethics is the study of goodness and badness.
If we could go back in a time machine to the year 1700 and offer 68-year-old John Locke a trip to our present day, I bet he’d be excited to see the development of the empirical sciences and the technological wonders that have sprung out of them. Thermodynamics, optics, chemistry, electricity — our mathematical mastery over phenomena that were in his day the subject of speculative philosophy would probably bring him to tears. But when he asked about ethics, I think he’d be saddened by our response. We’ve made no scientific progress in ethics. It’s still squarely in the realm of philosophy, and our attempts to turn it into an empirical science have failed.
This much we know: what’s good and bad must depend upon facts about consciousness. If there were no systems in the universe that had consciousness — the fact of there being something that it’s like to be that system — then there could be no good or bad, and there would be no ethics. There would just be things (or, somewhat more precisely, there would be everything, and nobody to take a perspective that would divide everything up into discrete things).
What we don’t know is basically the first thing about how consciousness works. We certainly don’t understand how affective valence — the subjective experience of goodness and badness — works. Without this understanding, there simply is no hope of developing a science of ethics. That’s why we need a science of consciousness.