To be fair, going by pure empiricism, it makes more sense to say that the world is non-deterministic. QM only matches observations iff we assume that the measurement process is truly non-deterministic. The Schrodinger equation can only be used, in practice, to measure probabilities, we don't know of any way to use to predict exact results.
However, philosophically speaking, this is unsatisfactory, since the behavior of the macroscopic world must somehow be reducible to the behavior of its constituents. If Schrodinger's equation were non-deterministic itself, we wouldn't have a problem - we could simply say "the world is nondeterministic, as far as we can see". If it at least was non-linear, with a possibility of chaotic effects, we could say "the world is probably deterministic, but it's impossible to measure it accurately enough to predict any definite outcomes" - but this is not the case.
So, we are stuck with this weird dichotomy between philosophy&logic on one hand and empirical observations on the other. MWI does give an out, but it has extra assumptions that are not directly justified any more than the Born rule (an observer only observes one world), and, more importantly, while it reproduces the Born rule in concept, it neither can derive it quantitatively.
Even worse, MWI can't explain how the classical world, where certain specific quantities are definite for all objects, arises out of the quantum world - the preferred basis problem. For example, a world where we observed some balls having a definite position, but others having a definite spin but not definite position, would be consistent with QM and the Born rule - and this indeed can happen in an experiment with particles. And yet we observe the same observables for all classical objects in our day to day lives.
I suppose it depends on whether we're simply stuck at too high a resolution of measurability due to Heisenberg uncertainty - either subatomic behaviour has a legitimate statistical factor, or we simply can't look low enough to see the deterministic factors (yet?)
This is straying into territory I can only hypothesise in though - for all I know the latter option may have already been ruled out. Does this dilemma map onto hidden variables vs Copenhagen interpretation?
My primary point of reference for these things is philosophical as I have an only-slightly-above-pop level of understanding of QM and am leaning more on second order cybernetics and epistemology to reason about observer-system interaction.
However, philosophically speaking, this is unsatisfactory, since the behavior of the macroscopic world must somehow be reducible to the behavior of its constituents. If Schrodinger's equation were non-deterministic itself, we wouldn't have a problem - we could simply say "the world is nondeterministic, as far as we can see". If it at least was non-linear, with a possibility of chaotic effects, we could say "the world is probably deterministic, but it's impossible to measure it accurately enough to predict any definite outcomes" - but this is not the case.
So, we are stuck with this weird dichotomy between philosophy&logic on one hand and empirical observations on the other. MWI does give an out, but it has extra assumptions that are not directly justified any more than the Born rule (an observer only observes one world), and, more importantly, while it reproduces the Born rule in concept, it neither can derive it quantitatively.
Even worse, MWI can't explain how the classical world, where certain specific quantities are definite for all objects, arises out of the quantum world - the preferred basis problem. For example, a world where we observed some balls having a definite position, but others having a definite spin but not definite position, would be consistent with QM and the Born rule - and this indeed can happen in an experiment with particles. And yet we observe the same observables for all classical objects in our day to day lives.