We should probably call it something like "causalism": using the word "real" to mean "that with which we could, in principle, interact causally." I include the "in principle" because there exist, for example, galaxies that are moving away from us so quickly they will someday leave our light-cone. We see their light today, and that's a causal interaction with the past galaxy where it used to be, but we understand enough about object permanence that we believe we have solid reason to infer there still exists a galaxy moving along the trajectory we witnessed, even when we cannot interact with it directly.