What Do We Mean by Fundamental?

What do we mean by fundamental? Let's see what David has to say, because he goes on to explain this. A phenomenon is fundamental if a sufficiently deep understanding of the world depends on understanding that phenomenon. The most fundamental phenomena are implicated in the explanation of many other phenomena, but are themselves explained only by basic laws and principles. So this is the idea that what fundamental means is explains a lot more than other things. It's still an idea that doesn't seem to have caught on universally, nothing's going to catch on universally, but it hasn't caught on in mainstream academia so far as I can tell.