I like the well-structured form of your detailed answer. From the viewpoint of natural philosophy, you offer plenty of criteria and comments on the current state-of-the-art how astrophysics deals with the question of cosmic expansion. Concerning several points from your answer I am a bit sceptical. - But the amount of space admitted to a comment is not enough to deal with all points. If you are also interested in the subject, what about breaking up your comment into several separate questions? Then we could discuss each point in more length. (1/2)

Let me just mention one point: dark energy is a hypothetical energy which generates a negative pressure(!). From a relativistic point of view, it is not enough to argue with energy or mass in separation. One has to combine energy, momentum and pressure into the physical quantity named energy-momentum tensor. Then a repelling negative pressure can counteract the attracting positive gravitational mass. The net-effect can be an expansion. (2/2)

@JoWehler As I'm am always striving to ferret out irrationality in my position, and that I would love to find consensus between our positions where you are skeptical, it seems to me that the best method to close our metaphysical differences, indeed, would be a series of questions where you have concerns.

On the details of expansion, I would suggest that my answer is an oversimplification that pays short shrift to the intricacies of the actual technical requirements of the argument. :D I'll read the paper Conifold cited if you have a particular bone to pick deriving from claims I've made here and address any perceived problems after coming to grips with the author's language.

@J D A good entry points seems to be in Guth's paper at p. 33 the section "The Inflationary Universe (Pressure of the False Vacuum)". He explains: "The negative pressure of the false vacuum, therefore, creates a repulsive gravitational field, which is the driving force behind inflation."

@J D Is the title question ill-posed? I do not know whether philosophy of science discusses this question. Recall that Kant in his first antinomy of pure reason rejects similar theses as ill-posed: “The world has a beginning in time” versus “The world has no beginning”. Do we have at our disposal the right concepts to formulate a question like this concerning the expansion of the cosmos? Which type of answer would we accept? (1/2)

@J D I don't understand the characterization of realism - instrumentalism, made by philosophy of science as described in the wikipedia link. Science does not aim at the “metaphysical in the universe”. Neither it deals with “nature’s unobservable objects”. It asks nature in the form of experiment and observation, and aims at understanding nature’s answer. Herefore, science creates theoretical models, often expressed in mathematical language. These concepts are not necessarily taken from observation. For an illustration see Feynman’s remarks in youtube.com/watch?v=xyVsTMrdOF4 (2/2)

The title is ambiguous as to whether it is technically one of physics or one of philosophy, and the votes for closure are largely because of a lack of imagination on the part of the voter. It is precisely because metaphysics studies the nature of reality that questions like what does it mean for the universe to have a beginning are at the heart of metaphysical discourse and aren't scientific questions. It is the embodiment of speculative metaphysics to try to generate language to tease apart what is and is not meaningful in this discourse. Historically religion has provided cosmogeny...

And the reason many fundamentalist Christian reject evolution is the same for attacking the Big Bang: BBT and NS are scientific theories that attack the supernatural characterization of God in the Bible. Science absolutely has purview over cosmogeny because we can draw inferences about such matters given the mathematical models we have related to the structure of space-time governed by both QM and GR. The problem is that many physicists don't recognize the legitimacy of...

theology in this domain, and many fundamentalists consider it an article of faith and refuse to do the science... in regards to understanding scientific realism and Instrumentalism, the latter starting with Duhem but reaching full force after the Linguistic Turn can be characterized by understanding that scientific theory always starts as metaphysical speculation linguistically, and then becomes integrated into a long body of theory based on natural epistemology that uses observation...

as a powerful tool for justification of belief. What Instrumentalism says is that by the standards of classical empiricism, the idea that our senses directly inform of us truth in the world, modern science has become something removed from touching, seeing, and smelling, and relies instead of complicated language that is underdetermined. For example, negative pressure isn't something we can see, touch, or taste, and therefore is a mathematical model primarily which doesn't tell us...

that something is physically real in the classic sense (space is a tensor is another good example of such a claim), but rather that what we accept is real is largely linguistic rather than sensory... in this way, science and metaphysics are not in competition, but that science is a particular type of successful metaphysics, because metaphysics is simpler and more primary to thought...

A metaphysical question is "What is the universe ultimately like?" to which there can be two types of answers: "It is like what God/Allah/Yaweh describes in the Bible" or "It is what our best scientists have shown through the scientific method as described by scientific literature". Thus, there are fundamentalist cosmogenies (Genesis is literally true), natural theological cosmogenies (Genesis is an important allegory prefiguring the Big Bang) or the international cosmogeny of astrophysics...

(Religious cosmogeny is distinct from and irrelevant to the science of the Big Bang theory). Instrumentalism is a way of seeing the Myth of the Given for what it is, a set of dominant values that presuppose in some non metaphysically necessary way the typical set of biases and values that presuppose the "objectivity" of the logical positivists.

Feynman is remarking on this, "that we see things in science" that are very far from our intuitions and what we would guess. For instance, GR says there is no simultaneity in spacetime. QM says that particles are both waves and particles. QM says that there are impossibilities in knowledge such as Heisenberg's principles. "Our imagination is stretched to the utmost to comprehend those things that are there" as he says... Instrumentalism is the approach to softening the approach of to deciding...

to weaken our logic to say there are not real and unreal things, but that reality and its boundaries is a little porous, and that if something is a wave and a particle, that's okay even though it contradicts our intuitions that something can't be two different things at once, because the theory is just a tool, it is not a claim about reality or what we observe with out senses directly.

Still reading the paper by the way. Gravitational suction is one interesting notion that the paper contains.