I am a beginner in philosophy and I am currently reading Jaegwon Kim's Philosophy of Mind. In the introduction (P.g. 8), Kim states that one of the most important problems in Philosophy of Mind is the relation between mental and physical properties which is called "the mind-body problem". He mentioned that we always believed that mental events and their physical effects are caused by neurons in our brain, but it was still something where philosophy is in charge of explaining. He gives explanations as below:
All that might be a complicated story, you say but it's something that neurophysiology, not philosophy, is in charge of explaining. But how do beliefs and desires manage to cause those little neurons to fire to begin with? How can this happen unless beliefs and desires are themselves just physical happenings in the brain? But is it coherent to suppose that these mental states are simply physical processes in the brain? These questions don't seem to be questions that can be solved just by doing more neurophysiological experimentation and theorizing; they seem to require philosophical reflection.
My confusion is that it feels to me those questions are still in the scope of neurophysiology, not philosophy, such as how mental desires to fire neurons. Would someone like to give me more explanations or some examples on it? Thanks in advance!