There are a lot of them! Just about everywhere you turn there’s a problem in metaphysics. But I suppose you just want to know what the main problems of metaphysics are. I’m going to give you and explain to you one that I think is extremely important Not all questions can be boiled down to this one, but I actually think that this issue lies at the center of many metaphysical disputes:

The Search for the Principium Individuationis.

I know, it’s Latin, but unfortunately philosophers like to use lots of latin in their technical terminology, probably an inheritance from the Medieval philosophers. But the problem of the, in English this time, principle of individuation, is one of the most fundamental metaphysics problems.

It asks the question: What makes a thing, an individual thing? What separates it from other things? Yes, I know you might roll your head at this question and think it’s a silly thing to ask. After all, isn’t it obvious when something is a single thing?

Not quite.

You might think at first that a chair is a single thing. But is it really? Aren’t atoms single things as well? If atoms are single things, and there are at least thousands (a physicist will have to correct me on this one) of atoms in a chair, then you can’t have thousands of single, individual things, in a single thing, a chair. Perhaps a chair is some kind of emergent thing? Not reducible to its atoms? But that seems a little spooky doesn’t it? Arrange atoms in a particular way, and all of a sudden a new thing pops into existence! So you might think that the single chair is just merely be a collection of atoms.

But then which atoms are the atoms which are in the collection which consist of the chair?

Is it just the collection of wood particles? Or does it also have some of the air particles around it contained within the collection as well? Why prefer any one collection of atoms over another when deciding which collection is the ‘chair’?

It would seem that any answer is entirely arbitrary. Collections of particles are just the ones we choose to collect.

Perhaps we might think that it’s not arbitrary if we add in the notion of function. A chair is a thing that can be sat on, so the only particles which should be grouped in this collection are the ones which help perform the function of ‘to be sat on’.

But then if we restrict it like this, aren’t there also wood particles in the chair that are inessential to helping perform the function? You could just scrape off some little bits of it, but it would still seem like those little bits of wood were part of the chair.

And now we just go onto puzzling even more about this question. See how hard it was to answer what the principle of individuation was even in this simple case of a chair?

Imagine how much more complicated it gets when you get to questions about personal identity? Or when you start asking yourself if the mind is distinct from the body?

Many people are under the impression that the issues of metaphysics are resolvable via common sense. I hope that the reasoning above has helped rattled up that impression a bit. Metaphysics is complicated, and really really hard. And as I’ve said before, it underlies almost every issue, philosophical or not, that we deal with in the world. - Ian Hedckman, PhD candidate in philosophy. https://www.quora.com/What-are-the-most-fundamental-problems-of-metaphysics

To assume metaphysics is dead is itself a metaphysical assumption. It's kinda like saying, “I don't believe in logic and I can reason just fine”. You just used logic to deny logic.

It's the exact same thing for metaphysics. You can't deny metaphysics but by way of metaphysics.

Metaphysics is kinda like the proverbial Phoenix that keeps arising from the ashes of its own destruction. Logical Positivism is now in the philosophical graveyard with the other boneheaded theories of bad philosophy. LP claimed,” Metaphysics is dead”! But the metaphysical spike in that claim came back to nail LP inside its own philosophical coffin. Hume, the hypocrite he was, abhorred all metaphysics but his own. Bertrand Russell thought he offed the idea of God as a necessary First Cause by claiming there is an infinity of numbers. Therefore, according to Russel, there is no logical contradiction in an infinity of cause and effect and no First Cause is necessary.

The reality is that infinity is a mental construct of mind. How can a finite mind comprehend it? What is infinity? And how does Russell know whether or not a greater infinity than infinity itself wasn't the First Cause of existence? We can do a metaphysical tap dance all the way around the philosophical dial here. You can't prove what infinity is, means, nor how it can exist in reality beyond the metaphysical construct of mind. Not only this, but nor can you prove whether a greater greater infinity exists beyond infinity. A greater greater greatest infinity could be the ultimate First Cause of infinity itself. The reality is that you can't off the idea of God. Even if Russell is correct that it's not a logical contradiction to have an infinity of causes, he still cannot tell us what infinity is nor whether there are greater infinities than infinity itself.

Metaphysics is kinda like Jesus Christ, you simply can't keep it in the grave . Metaphysics is always evolving and incarnating itself into some new theory , belief, idea or speculation about the nature of reality itself.

Reality is poisoned at the well and we have all been drinking the laced metaphysical moonshine of our own times and cultures. Politics, Religion, Science, Philosopy, Education, Entertainment, etc, etc. all have there peddled poison or metaphysical bent which is pure moonshine to some extent or another. But just as a rose is beautiful in spite of its thorns, all the dispensers of moonshine have elements of the beauty of Truth…just not the whole truth. Good metaphysics is needed if for no other reason than to counter the bad.

I would add that all fields of knowledge whatsoever including all of Science are grounded in metaphysical axioms or foundational first principles which are the necessary prerequisites in order to have any said field of knowledge. Try putting the empirical method under a microscope to validate its physical existence and it obviously cannot be done because the method is philosophical and theoretical in nature as is any field of knowledge. All fields of knowledge are dependent on a theoretical framework that is grounded in metaphysical axioms and assumptions of belief. All fields of knowledge whatsoever are evolving as the field takes in new information and expands its base of knowledge. If we knew what reality actually is there would be no need for Philosophy or Science. All knowledge is dependent on a metaphysical framework by nature and necessity of theoretics itself. Knowledge is inexhaustible and minds are finite. We can grow in knowledge and expand our base of theoretics but we cannot outstrip the metaphysical nature of reality itself nor theoretics in general. We have no choice but to philosophize and presuppose something about the nature of reality and existence itself. Hence, Man is a natural born metaphysician by default of the nature of reality itself.

I personally hold that Metaphysics is going to be the eternal haunting of Man so to speak. God has confined Man to an eternal abyss of metaphysics by divine fiat. God alone is ultimate reality and all else is created. Even those of us who claim to know God personally are never going to know him fully. But we will continue to grow in the knowledge of God for all eternity. Metaphysics is the main spice of life. We come from mystery. We live in mystery. We go back to mystery. It's all metaphysics. God isn't going to take the mystery out of eternity. Surely we will know God personally and intimately and grow in wisdom and knowledge. But don't think for a moment that we are not going to be eternally baffled by the mysterious awesomeness and mystery of God.

Mystery is an important part of life. Apart from mystery we lose our childlike wonder. We, like children, believe in the magic of life. God doesn't explain all the mystery of life simply because it would put an end to both Science and Philosopy.

Science is in some sense exploring the mind of God. Philosopy is in some sense exploring the reality of God. There is magic and wonder in both Science and Philosopy. If the magic of wonder does it's job and rubs off, we may be able to perceive the God behind this magical kingdom we call the universe. The universe itself is making a metaphysical argument for God via Science and Philosopy and of course it's own existence itself. Man has no choice but to do metaphysics in all his speculations. His only choice is to choose between good and bad metaphysics, metaphysical sobriety or metaphysical moonshine.

Perhaps, in some metaphorical sense, all creation and especially the creation of Man, is but the metaphysical wonder of God? - Todd Smith, former Natural Born Metaphysician. - -https://www.quora.com/Is-metaphysics-dead