What is the difference between on and upon?

Answer 1

'Upon' is simply a more specific version of on. It involves being on top of, or based above or over. For example if I throw paint at a wall, then there is paint ON the wall. It is on one of the surfaces but not necessarily the UPPER surface. I would not say there is paint upon my wall, and yet grammatically this still makes sense. This is because it is ontop of the wall, it is an additional layer. However this explanation often cause a common mistake to be made, which is to believe that 'upon' is the merging of the word up and on. And so to clarify we now look at something that doesn't involve layers, lets choose a computer monitor, and lets stick with the idea of paint. On my computer I open Paint, and I put lots of splodges of "Paint" on my screen. Now it WOULD be wrong to say that there is paint UPON my screen. It is not UPON my screen, but I can say that there is paint ON my screen (this would still confuse people though wouldn't it) however if there was both paint UPON my screen and ON my screen, at least I would be able to differentiate between the two. There is the REAL paint UPON my screen and the VIRTUAL paint ON my screen. At the start I mentioned that it can also be used to refer to being based upon something. It is common for someone to say 'I based this on..' but that is in fact a shortening of the word UPON. Here, what we mean to say is that we based our version UPON a version of something else. Much like building UPON an idea. I think the paint thing may have got a bit confusing but I think it kind of worked... The basics is that where you can use UPON you can always use ON, but where you can use ON you can't necessarily use UPON. UPON is more specific to things.