To me, modal realism seems particularly parsimonious to assume that if our world can exist, then any world that could exist does exist in "total reality", if only because to say "only our world exists" would require additional boundary conditions that somehow exclude all other worlds as being able to exist. These are extra elements in a theory that we cannot say exist, whereas I know at least one world exists.

I know others will say "you are positing all these other universes that we don't know exist". True - but we get a lot of nice explanatory power from that assumption and it doesn't presuppose entities that we don't know exist (worlds/universes) - only that we cannot think of any mechanism by which other worlds cannot exist.

For example, with modal realism, we can provide an objective and deterministic basis for probability/randomness.

Anyway, was wondering what the main arguments are against modal realism given all its strengths.

To me, modal realism seems particularly parsimonious - it assumes that if our world can exist, then any world that could exist does exist in "total reality", if only because to say "only our world exists" would require additional boundary conditions that somehow exclude all other worlds as being able to exist. These are extra elements in a theory that we cannot say exist, whereas I know at least one world exists.

I know others will say "you are positing all these other universes that we don't know exist". True - but we get a lot of nice explanatory power from that assumption and it doesn't presuppose entities that we don't know exist (worlds/universes) - only that we cannot think of any mechanism by which other worlds cannot exist.

For example, with modal realism, we can provide an objective and deterministic basis for probability/randomness.

Anyway, was wondering what the main arguments are against modal realism given all its strengths.