Even if we use a framework of rewards, it doesn’t make sense to differentiate between zero sum, negative sum, positive sum, constant sum, etc. without (a) assuming that we can compare rewards across people (so you find the congress seat as rewarding as I would, etc) and (b) having a baseline to compare to (the two of us arm-wrestling for a candy bar is zero sum compared to a baseline of us somehow having to split the candy bar between us no matter what, positive sum if compared to a baseline where we wouldn’t get any candy bar, and negative sum if we would have both gotten a candy bar otherwise).
Even if we use a framework of rewards, it doesn’t make sense to differentiate between zero sum, negative sum, positive sum, constant sum, etc. without (a) assuming that we can compare rewards across people (so you find the congress seat as rewarding as I would, etc) and (b) having a baseline to compare to (the two of us arm-wrestling for a candy bar is zero sum compared to a baseline of us somehow having to split the candy bar between us no matter what, positive sum if compared to a baseline where we wouldn’t get any candy bar, and negative sum if we would have both gotten a candy bar otherwise).