Pragmatic worries for metametaphysics

This is an interesting video blog on metametaphysics. Here's something the two philosophers did not explicitly mention: one way to cash out grounding or the fundamentality relation may be the cutting-nature-at-its-joints talk.

Perhaps an analogy would serve an explanatory purpose here. Some paintings are abstract, like say, cubism. Cubism still represents reality but perhaps not as accurately as say, a photo or a more fine grained painting. The cubist representations don't cut nature at its joints but does manage to pick out the same structures as the photo.

But I tend to have pragmatically inspired worries. Perhaps what we determine to be fundamental may largely depend on what we have uses for. So say numbers are often posited to exist because they serve useful purposes but if we can jettison them for something else that can do the job better (or maybe we manage to abandon whatever the job they serve to describe completely) we may not view them as fundamental or even real anymore. They don't cut nature at its joints at all; nature has no number joints.

Maybe tables, chairs and even people do not cut nature at its joints or at least cut it less fundamentally than more natural objects (perhaps subatomic particles or the cosmos as a whole?).

More specifically, say, tables are posited to exist because they serve an important role in society but table-chair composites do not and thus we may not see it as fundamental or as real as the table and chair individually. The table is physically separated from the chair, of course, but we posit the existence of many things that have parts vastly spatially separate from other parts (the solar system, e.g.). That may be because the solar system plays such an important roles in our society, our sciences and so forth. Likewise, the left-half of the table is seen as less fundamental or real as the whole table perhaps because it serves a smaller function for us. But say someday we stop using whole tables for whatever reason but find major indispensable uses of half-tables and forget all about whole tables. Will we then see whole tables as we do like table-chairs?

It may be more difficult to jettison the usage of some things than others because they are so culturally and socially and personally ingrained.

But pragmatic considerations come in degrees (which may explain the fundamentality or grounding relation) and are relative to societies and times (which may undermine essentialism or neo-aristotelianism).

Perhaps the sciences offer the best analogy here. At one time, Newtonian mechanics was a model that was thought to describe reality. But when Einstein came along, his model was then seen by scientists and common folk as a more accurate model which is more fundamental in a sense than Newton's. Scientists don't want to say that Newton was wrong maybe because his model still has practical applications in society. But say, one day, a model of physics will render both Newton and Einstein's theory useless (as an explanatory or any other kinds of tool such as a handmaiden for developing new technologies, say) and posit laws and objects that are so different from anything these two physicists posited that people may forget those other theories and call them false.

Here, you can say that it is because the new theory more accurately represents reality than the former two or you can say that it has more usages that the previous theories it has supplanted does not. What reasons do we have for the former explanation than the later?