Cosmology is the study of the origins of the universe, it's tied to astronomy.

Ontology, a branch of metaphysics, is the field of philosophy that discusses what kinds of being exist in the world.

Metaphysics is the field of philosophy that seeks to elucidate most general features of reality.

Cosmology has empirical accounts for some of the phenomenon observed and could be labeled as a science, though this can be debated to some extent.

Ontology is a mixture of observed phenomena and an priori classification and is subject to many different interpretations, often individual based.

Metaphysics is mostly a-priori. Whether the world is ideal, material, neutral or anything else, isn't really clarified by what we see in the world. Other aspects such as concept of the self, or free will and the like, may have some empirical components, but these are very slight compared with the innate concepts associated with these ideas.

So yes, there are important differences here.

Thank you for your answer! I wanted to provoke some thinking about and beyond the labels we have given to our fields of enquiry.
Metaphysics

Metaphysics is the field of philosophy that seeks to elucidate most general features of reality. — Manuel

Arguably, cosmology and ontology also try to elucidate exactly the same thing.

Ontology = why is there something rather than nothing and what is that something (Being)?
Cosmology = why is there something rather than nothing and what is that something (The Cosmos)?
Metaphysics = why is there something rather than nothing and what is that something (The Ultimate Reality)?

I think too many labels just lead to unclarity and confusion, when it is ultimately the same thing that we are curious about.

Roughly, ontology is what sort of stuff there is, cosmology is how it got there, and metaphysics is both. In recent parlance cosmology is the branch of physics that deals with the universe as a whole, and so is no longer a form of purely philosophical speculation. What counts as metaphysics varies with what metaphysics one adopts.

The terms are distinct, useful, and used.

I think too many labels just lead to unclarity and confusion, when it is ultimately the same thing that we are curious about. — TheArchitectOfTheGods

Well, maybe there can be confusion with ontology and metaphysics. So when Quine asks "What is there?", he is asking a question about ontology as he says, the answer he gives "Everything." applies both to ontology and metaphysics.

Cosmology shouldn't be confused with the others. It seeks empirical answers with a theoretical account that can explain phenomena. Metaphysics and ontology don't really have theories in this sense.

Metaphysics and ontology don't really have theories in this sense — Manuel

Yes so they are not sciences, in the sense that they are seeking to increase knowledge, but rather speculation or mental exercises beyond that which can be scientifically observed.
However, Cosmology is more and more involved in theorizing about concepts that cannot (yet?) be falsified by observation, e.g. when it comes to string theory, simulation theory, multiverse theory, information theory. Doesn't it then already cover the totality of the quest for what is there (ontology) and what is the ultimate nature of reality (metaphysics)? The line gets blurry here, because of course cosmology is seeking knowledge about ultimate reality. It is not about materialism, because physics itself found that the building blocks of matter are themselves immaterial, physics is so to speak 'catching up' with metaphysics (what used to be thought of as beyond physics).
I cannot argue the usefulness of these terms for others, if some people find them useful, then they are certainly useful for them, however I myself don't find them particularly useful.

The line gets blurry here, because of course cosmology is seeking knowledge about ultimate reality. — TheArchitectOfTheGods

By way of looking for laws of natures, yes.

I think the ontology and metaphysics do not look for laws in this sense, I'd wager they are based on experience as it pertains to our common understanding of the world.

But that's how I find it useful. If you don't find these distinctions useful, then that's what matters for you.

All inquiries are subsumed under metaphysics, for the excruciatingly simple reason that it is humans doing the work. The sciences may describe the conditions under which there are questions to ask, but it is metaphysics alone which determines what form the questions are given.

So, yeah, there are meaningful differences, easy to dismiss but impossible to ignore.

Cosmology vs. Ontology vs. Metaphysics
Are there really any meaningful differences between these terms? Or should we use them synonymously? — TheArchitectOfTheGods

Yes. No. I'd bet my last .02 cents on this quasi-Aristotlean scheme:

1.0 metaphysics (trad.) ~ why logic?

• how to derive [theology, ontology and cosmology] from logic?
• how to derive [axiology (ethics, aesthetics) & epistemology (science)] from theology, ontology and/or cosmology?

1.1 theology ~ why create natural systems (cosmos)?
1.2 ontology ~ why any natural system (cosmos)?
1.3 cosmology ~ why this natural system (cosmos)?

NB: Speculative cosmology [metaphysics] gradually became physical cosmology [physics] – wholly abstract 'why this cosmos exists?' reformulated into 'how this cosmos began and evolves?' increasingly grounded in explicable observations & evidence. :fire:

One of the elements that appeal strongly to me in Aristotle's De Anima is the way either we can talk about our experience of being organisms or not. Maybe it is not the basis for a complete explanation but it captures life trying to understand life in a manner few approaches do.

Cosmology vs. Ontology vs. Metaphysics — TheArchitectOfTheGods

Cosmology is a branch of physics. Ontology and metaphysics are branches of philosophy.

While cosmology is physics, and metaphysics is philosophy, the way I look at it is that they can work together to let us figure out how the universe works at its fundamental level because:

1. Metaphysics is the study of being and existence. It can theoretically be used to figure out why things exist and the properties of the most fundamental of existent entities.

2. Physics (and cosmology) is the study of the universe.

3. The universe exists and is made of existent entitites.

4. Metaphysics, through its ability to reason out the properties of the most fundamental of existent entities, can be used to deduce the laws of physics, cosmology and how the universe acts.

To me, this seems totally logical. I think this metaphysics-to-physics approach is a good method to get to the most fundamental laws of the universe. For me, in my amateur thinking about why things exist and the properties of existent entities, I'm trying to use these properties to build a simple model of the universe. If a model like this can make testable predictions, and these are validated by observation and experiment, this is science. It is the scientific method. Of course, this is easier said than done and I'm only just beginning, but I think this is a good method to use.
Anyways, it seems to make sense, and that's my approach.
Thanks.

NB: Speculative cosmology [metaphysics] gradually became physical cosmology [physics] – wholly abstract 'why this cosmos exists?' reformulated into 'how this cosmos began and evolves?' increasing grounded in observation & evidence. — 180 Proof

I think this is correct.
The ancients could only speculate what the ultimate nature of reality was (fire, water, air?). Now in the beginning of the 21st century we are a few very significant steps further, but not that much further really than where we started out. We can classify the world into 4 fundamental forces. It is physics (not philosophy) that is striving to combine the theories of these forces into a theory of everything (ToE). Speculative cosmology continues to become testable cosmology. But all is cosmology. We could say that metaphysics aka ontology is the speculative branch of cosmology, the one that provides the questions and impetus to continue researching, and physical cosmology is tasked with providing evidence or refutations. After all, only physical cosmology can hope to provide answers to the questions it continuously keeps creating by its new discoveries, since the days of Aristotle.

:up:

Yes so they are not sciences, in the sense that they are seeking to increase knowledge, but rather speculation or mental exercises beyond that which can be scientifically observed. — TheArchitectOfTheGods

Metaphysics, which includes ontology, proceeds by analysis and a process of 'abduction',whereby we identify logically absurd theories and reject them. Thus for some us it is a science of logic, and its main purpose is to increase our knowledge.

Your low view is shared by many including Russell, but this is only because Western academic metaphysics is hopeless. We should not blame the discipline.

Although it is speculative its results are often empirically testable in a negative way. For instance, metaphysics rejects the idea that matter is substantial and that space-time is real, and physics is unable to overturn this result. As far as anyone knows logic and experience coincide, so although metaphysics is a calculation, thus a speculation, we should not expect that it disagrees with physics in any respect. ,