What is metaphysics?
Metaphysics is the part of philosophy that asks what the world is really like. The word comes from Greek: "after physics". Physics asks how things move. Metaphysics asks what things are.
Big questions:
- What exists?
- What is a thing? What is a property?
- How is the mind linked to the body?
- What is time? What is a cause?
- Are we free?
We cannot answer these with a lab test alone. We use careful reasons, examples and thought experiments.
Ontology: what exists?
Ontology is the study of being, or existence.
- Concrete things are in space and time: a stone, a tree, you.
- Abstract things are not in space and time: the number 3, a triangle, justice.
Plato said abstract "Forms" are the most real things. Aristotle said the forms exist only inside real things. Nominalists say only single, concrete things exist; "redness" is just a word.
One or many?
Monism says reality is at bottom one thing (Parmenides; Spinoza; Advaita Vedanta's Brahman). Pluralism says there are many basic things (Democritus's atoms; the Nyaya-Vaisheshika list of categories).
Substance, properties, change and identity
A substance is the thing itself. A property is what the thing is like (red, round, heavy).
Change puzzled the Greeks. Heraclitus said everything flows: "you cannot step into the same river twice". Parmenides said real change is impossible. Aristotle solved it: the substance stays, its properties change.
Identity over time
The Ship of Theseus: replace every plank one by one. Is it the same ship? Possible answers: yes (same shape and history), no (no original parts), or "it depends what we mean by same". The same puzzle applies to people: John Locke said personal identity comes from memory; Buddhist thinkers say there is no fixed self, only a changing stream.
Mind and body
Is your mind the same as your brain?
- Dualism (Descartes): mind and body are two kinds of thing. Problem: how can a non-physical mind move a physical arm?
- Materialism / physicalism: only matter exists; thoughts are brain activity. Problem: how does matter feel pain or see red?
- Idealism (Berkeley): only minds and ideas exist. Advaita Vedanta also sees pure consciousness as the deepest reality.
The Samkhya school of India is also dualist: purusha (consciousness) and prakriti (matter).
Time, causation and the cosmos
Time: Does only the present exist (presentism), or are past, present and future all equally real, like points on a line (eternalism)? Saint Augustine said: "I know what time is until someone asks me." Kant said time is a form of how our mind orders experience.
Causation: a cause makes an effect happen. Hume noticed we only see one event regularly followed by another; we never see the "power" in between.
The cosmos: Why is there something rather than nothing? Is nature ordered by purpose (Aristotle's "final causes") or only by laws? Is life just complex chemistry, or something more? Science tells us how the universe changes; metaphysics asks what it all is.
Free will and determinism
- Determinism: every event, including every choice, is fixed by earlier causes.
- Libertarian free will: some choices are not fixed; you could really have done otherwise.
- Compatibilism (Hume, many modern thinkers): you are free when you act on your own reasons without force, even in a world of causes.
This matters for responsibility: praise, blame and punishment make most sense if people are in some way free.
Kant asked whether metaphysics is even possible: can reason know things beyond all experience? He said we know the world only as it appears to us.
Try it
Take a pencil. Sharpen it until half is gone. Is it the same pencil? Now imagine you replace its eraser, then its wood, then its lead. At what point, if any, does it stop being "your" pencil? Write your answer and one reason. Then use the 3D ship slider and compare.
Key formulas and definitions
- Metaphysics: study of the basic nature of reality
- Ontology: study of what exists (being)
- Substance = the thing itself; property = what it is like
- Monism (reality is one) vs pluralism (reality is many)
- Dualism (mind + matter) vs materialism (only matter) vs idealism (only mind)
- Determinism vs libertarian free will vs compatibilism
- Cause comes before effect; Hume: we see only regular succession
Worked examples
1. Is the number 7 real? Give two answers.
Platonist answer: yes, numbers exist as abstract objects, not in space or time; that is why 3 + 4 = 7 is true everywhere. Nominalist answer: no separate object exists; "7" is a useful word for counting groups of real things.
2. A river's water is always new. Is it the same river? Use Heraclitus and Aristotle.
Heraclitus: everything flows, so in one sense it is never the same river. Aristotle: the river (substance) stays while its water (parts and properties) changes, so it is the same river that has changed.
3. A robot says "I feel sad". What would a dualist and a materialist say?
A dualist: the robot has no non-physical mind, so it only imitates sadness. A materialist: if its physical system works like ours, it might really feel; feeling is what certain physical systems do.
Common mistakes
- Thinking metaphysics means magic or the supernatural. In philosophy it is careful reasoning about reality.
- Mixing up substance and property: "red" is a property; the apple is the substance.
- Thinking determinism means fate that happens whatever you do. It says your choices are themselves links in the chain of causes.
- Thinking science has already answered all metaphysical questions. Science describes how things behave; questions like "what is a cause?" remain.