Philosophy Versus Cosmology

The Role of Philosophy in Cosmological Development
As it has been observed throughout this course, philosophical thought has a lot to do with cosmology. It can be said that philosophy played a role in the progression of cosmology from the early 1900s to the present-day cosmology. Quantum mechanics, for example, is a part of science that is subject to philosophical thought simply because our abstract way of understanding it.
One of the classical philosophical problems is simply whether the concept of the universe has any physical meaning or if it is just an idea, and this problem obviously depends on another one, namely, what is to be understood by the "universe." I started by mentioning that "universe" normally means the totality of physical things, but many scientists would add a further clause, namely, that these things have to be causally connected; since cosmologists happen to be situated on earth, this means that the universe, according to this view, is that part of spacetime and its physical constituents that are accessible in principle to observers on earth. This is an empirically reasonable definition which limits the universe to a spatial radius of the order of cT, or about 10 billion light years, but it is clearly a definition that ignores the multitude of things outside this radius. According to most cosmological models there is a cosmic horizon outside which galaxies recede from us with velocities larger than that of light, and which are therefore unobservable even in principle. Yet these objects too belong to our universe, in the wider sense, and we therefore have to accept that cosmology deals with objects that are unobservable in principle, which of course is a philosophically controversial claim, especially to empiricists.
Cosmological knowledge seems to be conditioned by principles or assumptions that are themselves completely unverifiable insofar as they can only have a limited inductive support. The most important of these assumptions is...