Metaphysics

Plato and Aristotle (right), by Raphael (Stanza della Segnatura, Rome). Aristotle is regarded as the "father" of metaphysics.

Metaphysics ( Greek: μετά (meta) = "after", φυσικά (phisiká) = "those on nature", derived from the arrangement of Aristotle's works in antiquity) is the branch of philosophy concerned with explaining the nature of the most fundamental aspects of the world. It addresses questions such as: What is the nature of reality? Does the world exist outside the mind? What is the nature of objects, events, places? Is free will possible in a world governed by causal laws?

A central part of metaphysics is ontology, which is aims to understand which things exist. Ontology is, one might say, an attempt to determine what the most basic building blocks are out of which the rest of reality is constructed. Philosophers of different times have shown different levels of optimism with respect to how much ontology can accomplish. Plato, for instance, appears to have thought that it is capable of showing the existence of entities which are outside of the sensible world, but which play some key role in determining the nature of that world. Many philosophers in the 20th century, however, saw ontology as, at best, an attempt to understand the relations between a certain set of concepts we use, such as that of substance, property and relation.

It is important to distinguish the sense of 'metaphysics' employed by philosophers from a different sense it has acquired relatively recently: one associated with spirituality and world-transcending thought. Though the latter usage has its historical roots in the former, almost all contemporary metaphysicians cringe when they walk by the 'Metaphysics' section of bookstores.

Because it concerns itself with fundamental questions, nearly every major philosopher has devoted a certain amount of thought to metaphysics. This means, however, that a history of metaphysics would be little less than a history of all of philosophy. This article will therefore survey the issues that have most concerned metaphysicians throughout history. A list of historical figures especially worth considering is provided at the end.

Five central questions of metaphysics

Mind and Matter

One of the central issues in metaphysics concerns how to understand the relation between minds and the world they exist in. More specifically: whether the most basic constituents of mind and the world were one and the same. Democritus and Epicurus, for instance, claimed that the world was fundamentally made up of indivisible particles, but held that the mind was simply a special sort of particle. Descartes held that the material world was composed of material substance, and so fundamentally unlike the intellectual substance that was minds. Spinoza and Leibniz claimed that all of the finite world had both physical and an intellectual aspects - so that even the most simply physical particle in some sense had a mind. An even more radical position is that of Berkeley, who claimed that the material world is nothing more than ideas.

The root issue is that, in the task of trying to understand what the world is made up of, the metaphysician is faced with the fact that minds and matter appear to have very different natures. One is conscious, the other isn't. One appears to be divisible and complex, whereas the other seems simple. Yet the two also appear to interact, and it is plausible (as Spinoza explicitly states in Book 1 of his Ethics) that only things with something in common can interact. Further, we intuitively take ourselves to possess at least some knowledge about the nature of the world (especially as the result of science), and this seems to require that the divide between mind and world not go too deep.

See also Appearance and Reality and philosophy of mind.

Objects and their properties

In looking at objects in the world, we often will look for things they 'have something in common.' For instance, we might say that two apples have the same color, that two people are the same height, or that two books have the same number of chapters. But what is the nature of these entities that are 'had in common'? They do not appear to be particular objects - these claims are not like the statement that two people might have a friend in common. The things appear to be 'universal,' not particular, in that they can be fully present in many things.

There are two related questions one might raise about universals like redness, roundness, etc. The first concerns their ontological status: in what way do these things exist? For instance, would redness still exist even if there weren't any particular objects that were red? After all, we don't think that destroying one red thing has any effect on redness itself, so why would the destruction of all of them do so? But if redness could exist without any particular red objects, then it must in some way be independent of them. This points to the second question: what is the relation between universals and particulars? Are particular objects something more than just a sum of universals, and if so, what? This latter question has a close relation to the issue of change (discussed below).

The most extended discussions of this problem in ancient philosophy are found in the dialogues of Plato (in particular, the Parmenides). In much of his work, Plato argues that universals are more real than particulars, and philosophers who defend the claim that universals have some sort of independent existence are often called 'Platonists.' The opposing view, called 'nominalism,' holds that universals exist only in name - in other words, that we merely have words that are applicable to many objects, but that there is no sense in which the words refer to some entities that are separate from particular objects.

See also Universals.

Identity and change

Puzzles associated with change go back at least to Heraclitus' famous claim that "you cannot step into the same river twice". As it is most often interpreted, Heraclitus is making the following point: we take there to be a single river from moment to moment, but since there is a change in what is present (for instance, a difference in water levels), it cannot be strictly true that the same river is there. That is, consider the following two claims:

1. The river has the property of being 4 meters deep on Tuesday
2. The river has the property of being 3.5 meters deep on Wednesday.

But since no river can be both 4 meters deep and 3.5 meters deep, it would seem that the river we find on Tuesday cannot be the river we find on Wednesday.

One option is to accept the claim that the same river cannot be present at two times if there is any change. Yet this would lead us to claim that very few of the things we thought lasted through time do, since almost everything in the universe undergoes at least some change from moment to moment. Many philosophers have therefore tried to find ways to vindicate our talk of persisting objects that don't involve the unacceptable claim that the same object can have incompatible properties.

One option is to deny that it is correct to say that (for instance) the river has both the property of being 4 meters deep and the property of being 3.5 meters deep, since those properties are incompatible. Rather, one might insist, the river has two properties that can be described by the phrases 'being 4 meters deep on Tuesday' and 'being 3.5 meters deep on Wednesday.' The properties described by those phrases are obviously compatible. We might describe this solution as one of time-relativizing the properties themselves.

Another option is to see the object as broken down into 'time-slices.' The river is then seen as some sort of composite of slices that might be referred to by phrases such as 'the river on Tuesday' and 'the river on Wednesday.' On this view, it's not strictly true that the properties of being being 4 meters deep and of being 3.5 meters deep are ascribed to the same object. Rather, they are ascribed to different objects (the time-slices), which are components of some larger bobject. This solution can be described as time-relativizing the objects.

A third option is to relativize the relation between the object and the property. On this view, the above statements should be recast as: "The river is-on-Tuesday 4 meters deep" and "The river is-on-Wednesday 3.5 meters deep."

Though these distinctions seem overly subtle, the ramifications of the choice are very significant, for this is a choice about how to understand one of the most fundamental features of the universe: change.

The structure of space and time

Space and time are some of the most basic features of the world. Things have spatiotemporal locations, and spatiotemporal relations to each other. One of the longest-standing metaphysical questions about space and time concerns how to understand the relation between locations and relations.

A number of philosophers, including the great physicist Isaac Newton, have considered the notion of location to be more fundamental than that of the relations. They saw space, in particular, as a sort of substance, which is in principle capable of existing on its own. What explains two objects being, say, 20 miles apart on this view is some more basic facts along the lines of:

1. Object A is at location 0,0,0.
2. Object B is at location 20,0,0.

The opposing line of thought, advanced by philosophers such as Leibniz, held that relations are more basic than locations. But relations, obviously, only exist insofar as there are objects that are related. This in turn means that objects are more fundamental than their relations, and so more basic than space and time. Our talk of particular locations, for someone like Leibniz, is merely a short-hand for describing relations between objects.

One of the key arguments Leibniz gave for his view was the following: assume that the Newtonian view is correct. In that case, it is possible that every object in the universe be moved two feet to the left, changing absolute location, but with no change of relations. In Leibniz's own case, he appealed to God's rationality at this point, asking what reason God could have for choosing one location rather than another for the universe, and concluding that the question must have been confused to begin with. More recent philosophers have run the argument without the appeal to God, merely using it to point out the superfluousness of absolute location.

In response, Newtonians have worried whether it is intelligible to see space (and time, for which exactly similar arguments apply) as being dependent on objects in the way Leibniz's view requires.

See also Space and Time.

Determinism and Free Will

One of the most recurrent philosophical problems comes from the apparent incompatibility of two independently plausible claims:

1. Everything in the universe is causally determined, and what is causally determined could not have been otherwise.
2. In acting in the universe, we sometimes could have done otherwise than we actually do.

The first question addressed by philosophers on this point is whether the claims are in fact incompatible.

'Compatibilists' claim that the apparent inconsistency of free will and determinism can be avoided if we properly specify what each claim means. For instance, a compatibilist might claim that the 'could have done otherwise' in (2) isn't about what really could have been otherwise, but perhaps merely what would have been otherwise if (as was in fact impossible) one had had a different set of desires of beliefs.

'Incompatibilists' are those who find no compatibilist solution acceptable, insisting that no incompatibilist way of understanding the claims actually captures what was originally meant. Given this, incompatibilists think we have a choice between rejecting one claim or the other. 'Libertarians' reject (1), insisting that their confidence in the freedom of their wills is sufficient to convince them that the universe cannot be causally determined. 'Hard determinists' reject (2), concluding that the freedom of our will is a mere illusion (both Spinoza and Hume offer interests diagnoses of our tendencies to believe that our wills are free).

A small number of recent philosophers have thought that developments in modern physics offered some help on this issue, particularly developments that suggest that there is no genuine determinacy. Unfortunately, the lack of determinism in such theories doesn't appear to be in the right 'place'. For instance, the fact that the location of particles is not determined by antecedent conditions doesn't seem to make room for our wills to be free, for the general laws of psychology still hold well enough.

See also Determinism.

Criticisms of metaphysics

Though some metaphysical projects have no ambitions beyond conceptual analysis, others have, to varying degrees, attempted to make substantive claims about the nature of reality (Plato again being a prime example). But the very suggestion that philosophers are in a position to discover substantive conclusions about the fundamental aspects of reality has struck many thinkers of an empiricist bent as patently absurd. This most frequently takes form as a challenge to whether such metaphysical claims can be justified, but an important movement known as logical positivism denied that metaphysics claims could even be meaningful.

Criticisms about justification

The line of thought that has lead some philosophers to claim that metaphysical statements cannot be justified runs roughly as follows: (1) metaphysical statements are about the world, and (2) all we know about the world we learn through our senses. Yet, as metaphysicians themselves admit, (3) metaphysical claims cannot be justified merely on through our senses. Therefore, metaphysical claims cannot be justified. Such a sentiment is especially obvious in some of the writings of the Scottish philosopher David Hume:

"If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion".

- An Enquiry Concerning Human Understanding

The obvious premise for the metaphysician to reject in the above argument is (2), the claim that all we know about the world is based in our senses. Plato, for instance, held that prior to birth, we encountered more fundamental aspects of reality, and merely need sensory promptings to recall those aspects. Descartes held that God had imprinted certain basic ideas in our minds in creating us, and that we could draw substantive conclusions from those ideas.

Kant, while being sympathetic to the basic anti-metaphysical argument, only accepted a qualified form of premise (1), the claim that metaphysical statements are about the world. He held that some metaphysical claims (such as 'every change has a cause') are not about a world that is completely independent of us, but rather about how objects appear to us. Moreover, the way that objects appear to us is partially determined by features of our own minds, and it is by knowing about those features that we can be justified in substantive claims about how objects will appear to us.

Criticisms about meaningfulness

Logical positivism, a movement started in Vienna that held a strong following in Britain, advanced a strong form of 'verificationism,' the view that the only meaningful statements were those that could in principle be verified by some set of observations. The positivists intended to use this view, which has at least some intuitive appeal, to do away with a large portion of religious doctrine and metaphysical disputes.

Three important features of most substantive metaphysical statements, such as 'every event has a cause', are their universality, necessity and non-analyticity. In other words, they say that, with respect to entire group of things (e.g. events), that each member of that group cannot exist without having some feature (e.g. 'having a cause'), even though that feature wouldn't be mentioned in a fully adequate definition of the group. The most experiential observations can show us, however, is that some particular thing actually has some feature. No set of observations can establish any non-definitional property of everything in a group, so all metaphysical claims would fail the verificationist test.

While it enjoyed considerable popularity for a time, the positivist project was eventually abandoned, for it became apparent that core statements of scientific theories (e.g. the statement of universal gravitation) share some of the features of metaphysical statements, and so cannot be directly verified by observations. In the wake of positivism, their lessons were taken instead to show that metaphysical statements are not meaningless statements, but rather that they are generally not fallible, testable or provable statements (see Karl Popper).

Major metaphysicians

Peter Abelard Aristotle Thomas Aquinas St. Augustine Avicenna (Ibn Sina) George Berkeley Boethius

René Descartes Georg Wilhelm Friedrich Hegel Martin Heidegger Immanuel Kant Gottfried Leibniz John Locke Plato

Plotinus Willard Van Orman Quine Bertrand Russell Jean-Paul Sartre Arthur Schopenhauer John Duns Scotus Baruch Spinoza

Recommended reading

• Gale, Richard M. (2002). The Blackwell Guide to Metaphysics. Oxford: Blackwell.
• Kim, J. and Ernest Sosa Ed. (1999). Metaphysics: An Anthology. Blackwell Philosophy Anthologies.
• Kim, J. and Ernest Sosa, Ed. (2000). A Companion to Metaphysics. Malden Massachusetts, Blackwell, Publishers.
• Lowe, E. J. (2002). A Survey of Metaphysics. Oxford: Oxford University Press.
• Loux, M. J. (2006). Metaphysics: A Contemporary Introduction (3rd ed.). London: Routledge.

External links

• Aristotle's Metaphysics trans. by W. D. Ross
• Aristotle's Metaphysics trans. by Hugh Tredennick (HTML at Perseus)
• Aristotle's Metaphysics at Stanford Encyclopedia of Philosophy
• Hume's Enquiry Concerning Human Understanding: Mirrored at eBooks@Adelaide
• E-text (The Norman Kemp Smith translation of Kant's Critique of Pure Reason)
• Stanford Encyclopedia of Philosophy on metaphysics
• Stanford Encyclopedia of Philosophy on change, by Chris Mortensen
• Stanford Encyclopedia of Philosophy on properties, by Chris Swoyer
• [http://plato.stanford.edu/entries/freewill/ Stanford Encyclopedia of Philosophy on

free will, by Timothy O'Connor]

• Stanford Encyclopedia of Philosophy on relativism vs. absolutivism about space and time, by Nick Huggett and Carl Hoefer

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

• Metaphysics  ^history

The history of this article since it was imported to New World Encyclopedia:

• History of "Metaphysics"

Note: Some restrictions may apply to use of individual images which are separately licensed.