A philosophy professor friend of mine rejected the use of Occam razor to
justify the many-world interpretation. He pointed out to me that
classically Occam razor aims at simplifying the object, not the theory
behind the object.
The way he sees it, the many-world interpretation achieves a simple
theory at the expense of a very large object, and therefore, cannot be
justified by the classical Occam razor. This point is one of the
favorite criticism of the anti-many-worlder advocates. Thus Occam razor
can only be used if we are very clear about its meaning: the simplest
theory is selected rather than the simplest object.
The history of science, and in particular Astronomy has been an
expansion of our horizons. The perceived world has been getting larger
and larger and more and more complex as science progresses. Let's be
clear when we talk about Occam.