Kathyd wrote:When I think of the term "physical", I'm usually thinking of an object I can see and touch, like a stone or a brick. It is even a common context for the word to be used to describe the properties of our bodies, as opposed to "mental".
However, when I think of "matter", I think, or at least can think, in a much more broader context. I think of "stuff" - atoms, molecules, dark matter, electrons, protons, etc - a broad collection of things, many of which are invisible, intangible, and some of which their existence is only theorized based on evidence (dark matter).
"Matter" appears to be a much more general and even abstract concept, while "physical" appears to normally designate a much more specific and concrete concept. For example, saying something has "physical" properties to me implies it much be composed of some kind of matter. But just saying "matter" does not imply to me at all that the substance in question even has any known or defined properties at all. In other words, it appears that anything "physical" must also be "matter", but it doesn't necessarily follow that anything made of "matter" must also be considered "physical".
That might not corroborate with the standard definitions, but I think intuitively most people do differentiate between these two terms, at least in a subtle way.
* First all of, if "physical" were defined as "nonmental", then dualism would be true by definition—which it shouldn't be. From the perspective of materialism, the mental is part of the physical, being the psychophysical
and thus a type of physical phenomena.
"We have a tendency to read 'nonphysical' when we see the word 'mental', and think 'nonmental' when we see the word 'physical'. This has the effect of making the idea of physical reduction of the mental a simple verbal contradiction, abetting the misguided idea that physical reduction of something we cherish as a mental item, like thought or feeling, would turn it into something other than what it is. But this would be the case only if by 'physical' we meant 'nonmental'. We should not prejudge the issue of mind-body reduction by building irreducibility into the meanings of our words. When we consider the question whether the mental can be physically reduced, it is not necessary—even if this could be done—to begin with general definitions of 'mental' and 'physical'; rather, the substantive question that we are asking, or should be asking, is whether or not things like belief, desire, emotion, and sensation are reducible to physical properties and processes. We can understand this question and intelligently debate it, without subsuming these items under some general conception of what it is for something to be mental. If 'mental' is understood to imply 'nonphysical', it would then be an open question whether or not belief, desire, sensation, perception, and the rest are mental in that sense. And this question would replace the original question of their physical reducibility. We cannot evade or trivialize this question by a simple verbal ploy."
(Kim, Jaegwon. "The Mind-Body Problem at Century's Turn." In The Future of Philosophy
, edited by Brian Leiter, 129-152. Oxford: Oxford University Press, 2006. p. 138)
* Yes, the naive idea of a physical object is that of a sensible solid body. For example, a stone is paradigmatic physical object. But even if the physical is equated with the corporeal, philosophers use a much broader concept of a body. For example:
"Body is whatever coincides or is coextensive with a part of space, and does not depend on our thought."
(Hobbes, Thomas. Elementorum philosophiae, sectio prima: De corpore
(1655, Engl. 1656), Part II, Ch. 8: Body and Accident, 8.1 The Definition of "Body")
Given this definition—according to which a body is a filled volume or filling of a volume of space—, bodies needn't be solid, and e.g. a mass of water and a mass of air are bodies too.
* In physics, the concept of matter is used to refer to the elementary particles and all systems composed of elementary particles. These are the material objects, and matter is then the totality of material objects. But "matter" can also be used to refer to the universal stuff of which all elementary particles consist, such that they are different forms of it.
* Of course, it's a matter of definition; but it makes no sense to deny that all material entities are physical entities. Are all physical entities material entities? Well, if "material" is defined narrowly in terms of (solid, liquid, or gaseous complexes of) elementary particles, then there are physical entities which aren't properly called material such as electromagnetic fields, gravitational waves, and regions of space.
* The contemporary materialist/physicalist philosophers agree with Jack Smart:
"For me, the material is just the physical, and I feel entitled to believe in all the entities which the physicist needs to assume."
(Smart, J. J. C. "The Revival of Materialism." 1976. In Essays Metaphysical and Moral: Selected Philosophical Papers
, 240-245. Oxford: Blackwell, 1987. p. 240)
That is, in this very broad and general sense of the term—in which "physical" means "physics-al"/"physicSal"—, an entity is physical if and only if it belongs to the (nonpsychological) ontology of physics or is nothing over and above a complex or system of entities belonging to that ontology.