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Define Physical

  1. Jan 5, 2005 #1

    Les Sleeth

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    Debates about physicalism are sometimes hampered because participants can't seem to agree what "physical" is. I'd like to invite all physicalists and those who believe they are clear about what physicalness is to create an exact definition.

    I'll offer my opinion first. I think physicalness is mass, immediate effects of mass, and all that which has come about from the presence of mass. Since all mass we know of is believed to have originated with the Big Bang, then I'd also restrict the definition of physical to how mass and mass effects have developed from that event.

    In a past thread I posted the following in support of my definition:

    Princeton's Word Reference site give the definition of physical science here:

    - the science of matter and energy and their interactions


    On the same page you can find a definition for physicalness:

    - the quality of being physical; consisting of matter


    The Word Reference site gives several relevant definitions of physical here:


    1* physical - involving the body as distinguished from the mind or spirit . . .
    2* physical - relating to the sciences dealing with matter and energy; especially physics; "physical sciences"; "physical laws"
    3* physical, tangible, touchable - having substance or material existence; perceptible to the senses; "a physical manifestation"; "surrounded by tangible objects"
    4* physical - according with material things or natural laws (other than those peculiar to living matter); "a reflex response to physical stimuli"
    6* physical - concerned with material things; "physical properties"; "the physical characteristics of the earth"; "the physical size of a computer"


    Of Physicalism the Wikipedia says:

    Physicalism is the metaphysical position that everything is physical; that is, that there are no kinds of things other than physical things. Likewise, physicalism about the mental is a position in philosophy of mind which holds that the mind is a physical thing in some sense. This position is also called "materialism", but the term "physicalism" is preferable because it does not have any misleading connotations, and because it carries an emphasis on the physical, meaning whatever is described ultimately by physics -- that is, matter and energy.
     
    Last edited: Jan 5, 2005
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  3. Jan 5, 2005 #2

    StatusX

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    I would define physical laws as those laws that can be framed in the language of mathematics. Or less strictly, the language of logic. For example, if we find a theory of consciousness that quantitatively relates experiences to information processors, as Chalmer's suggests, I would call this a physical theory of consciousness. This raises the question of whether the universe is mathematical or merely approximated by math. If it's the former, then physicalism completely describes the universe, with the possible exception of its creation. If its the latter, physicalism, at least as we know it today, will fall short.
     
    Last edited: Jan 5, 2005
  4. Jan 5, 2005 #3

    Les Sleeth

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    You might be correct, but I haven't asked for what physical "laws" are. That is entirely different! Once you reduce physicalness to the abstraction of laws and logic and math, you've put the ball squarely in your own (physicalist) court. Physical might follow laws, and be predicted by math, but that isn't what it is.

    Please stick to a definition of physicalness itself. What is it?
     
  5. Jan 5, 2005 #4

    StatusX

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    Ok, then I would define physicalism as the position that every observable process is completely determined by physical laws, as described above. To put this another way, if two systems are identical in every physical way, they cannot be different in any other way. By "physical way" I mean whatever parameters go into the final mathematical theory (eg, matter, space, qualia). As for unobservable processes, I would say that physicalists deny such a thing could exist.
     
  6. Jan 5, 2005 #5

    Les Sleeth

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    I'm sorry if I've confused the issue. I didn't ask for a definition of physicalism. I am asking what "physical" means. What are the properties of physicalness? How can you tell if you are looking at something physical (without any reference to laws or calculation)? What qualities, if observed, would make an objective thinker say, " that is physical"? What qualities, if observed, would make an objective thinker say, "that's not physical"? You can't cite obeying "laws" because those are determined after the fact of consistantly observing the same qualities. I am asking for what can be observed in the raw, one time, that makes something physical.
     
  7. Jan 5, 2005 #6

    StatusX

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    I'm sorry. The reason for the confusion is probably that (and to answer your question as best I can) as a physicalist, I believe everything is physical, and the question doesn't really make sense to me. And I don't see how you can say anything about the world without some basic rules. Don't forget, the mass and energy in your own defintion are not intrinsic qualities, but only arise from the rules we have discovered to describe functional relationships.
     
  8. Jan 5, 2005 #7

    Les Sleeth

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    You are admitting to a lack of objectivity. How can anyone trust such an opinion? What if someone comes along and picks out of reality only that which gives support to their spiritual beliefs, and ignores anything which doesn't?

    For a minute, can't you just look at reality without your filters and concepts in place and describe what you see that is physical? We can argue later what is birthed by physicalness and what isn't.

    Let's just define the OBSERVABLE properties (for now) which most define physicalness for what it is.
     
  9. Jan 5, 2005 #8

    StatusX

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    Anything that we can observe must have at least intitiated a physical process since our senses are physical. Assume we observe something "non-physical" and we can trace the physical processes back somehow from where they interacted with our senses to point where the laws of physics are violated (as they must be since otherwise the phenomenon would be physical). Now I can't think of anything like this, but if it exists, I would say that all it means is our laws are incomplete, and as long as the additional laws followed some kind of basic logic, preferably framable with math, a physicalist view can be sustained. If they can't, well have to rethink a lot of things, but I'm sure many scientists would first die trying.

    One other possibilty that comes to mind is that a phenomenon can strictly follow the laws of physics, specifically quantum mechanics, but the chances of it happening the way it did are so astronomically small that pure luck can be ruled out. (eg, a ten foot tall gold crucifix spontaneously forms from atoms in the air) Again, I'm sure many, many alternative theories will be proposed by scientists first, and maybe they'll find one that works.

    So, for my fourth try, I'll say that phenomena are non-physical if they cannot be explained using logic or math or if they can be, but something so unlikely has happened that some unseen force must be responsible. If this isn't what you wanted, I think I'm gonna have to give up.
     
    Last edited: Jan 5, 2005
  10. Jan 6, 2005 #9

    loseyourname

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    Given his framework, the definition of physical would be "anything that obeys mathematical laws." This would be about the same as the definition I developed in another thread for you. The word "physical" describes the property of having predictable extrinsic relationships. This is borrowed from theory-physicalism, which excludes all instrinsic properties, making it meaningless to ask "What is an intrinsic property of physical things?" Mass is not an intrinsic property, so your own definition doesn't tell you what physicalness is by your own standards. Furthermore, massless particles are generally considered to be "physical."
     
  11. Jan 6, 2005 #10

    selfAdjoint

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    I think that the definition of what is physical evolves along with physics. Once upon a time when Descartes wrote, physical meant pushes and pulls by macroscopic matter, then there was gravity, and chemical bonds, conserved energy, and luminiferous ether, and so on. At each point people who espoused physical philosophies (Locke, Marx, the log-pos group) used the then current notion of physicality.

    Today physicality pretty much means consistence with the Standard Model of particle interactions or with General Relativity (locally GR looks like Special Relativity so that is included too). Those theories are accepted by physicists as "effective", matching all experiments we know how to do now, and there is enormous experimental support for their predictions at all energy scales likely to be relevant to the human body.

    People who use speculative theories beyond these have to carefully state their assumptions, and their conclusions can only be accepted modulo the theory they posit.
     
  12. Jan 6, 2005 #11

    Les Sleeth

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    Would the part of your post I selected be a concise definition? I would love to have a tight definition, one which states the absolute minimum needed to qualify as physical. That would help to judge if something is physical, or uf something is a trait of physicalness (a common dispute in debates). Let me give an example.

    If I say one requires balance to ride a bicycle, can I then go on to say riding a bike is anything that requires balance? That sort of logic is what I don't like about the definition Loseyourname and StatusX give. They basically define physical as anything subject to logic and/or which obeys mathematical laws. I've disputed that because I don't see why some cosmic consciousness would not have particles and not be subject to relativity (using your definition now), and yet still have ordered aspects to it which could be represented logically or mathematically.

    Let me ask you one thing more (well, it's several questions about the same thing). Do you think my definition is generally correct (that "physicalness is mass, immediate effects of mass, and all that which has come about from the presence of mass")? Do you think it automatically includes your elements (i.e., quantum and relativity factors)? Do you think it is more basic than your definition? Maybe too basic? If so, do you think my definition would be improved by adding yours, something like this:

    "Physicalness is mass and the effects of mass, and exhibits consistency with the Standard Model of particle interactions or Relativity."
     
    Last edited: Jan 6, 2005
  13. Jan 6, 2005 #12
    What a great question. Would the statement:

    "Something is physical when it can be observed" be acceptable? Have I changed the game by rewriting the way the statement is said? "Physicalness" would then be something that is observable.

    By the way, I don't personally consider your definition "that physicalness is mass, immediate effects of mass, and all that which has come about from the presence of mass" particularly good, because the concept of mass has become so exceedingly abstract and intermingled with other ideas. For example, light has no mass (though it has momentum) and yet I would consider it a physical thing. The fact that light can push seems to eliminate the possibility of it not being physical, and yet does not give it any mass.
     
  14. Jan 6, 2005 #13

    Les Sleeth

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    A photon has no rest mass. However, I understand what you are saying, which is why possibly the addition of inertia should be added to the definition. I've quoted the following before from the the McGraw-Hill Encyclopedia of Science and Technology: “The distinguishing properties of matter are gravitation and inertia.”

    In terms of being observable as the definition, I don't think that tells us anything about physicalness itself; i.e., it's properties, nature, requirements for existence. Physicalness would still exist, for example, even if no one observed it.
     
    Last edited: Jan 6, 2005
  15. Jan 6, 2005 #14
    Yes, but I didn't say something had to be observed to be physical, just that it had to be observ-able. One might argue that there are things that can be observed that aren't physical, such as love and anguish, but wouldn't a physicalist argue that those were, in fact, observable in a physical sense?

    I still like my definition best. But then what do you expect? :tongue2:
     
  16. Jan 6, 2005 #15

    selfAdjoint

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    First of all, I would accept the quote you selected as what physicalism means to me, and I would add an annex, not to add to but to explain that quote. Systems like electromagnetism and Newtonian physics are specializations of the standard model and general relaivity, valid under certain retrictive conditions which conditions are generally true in the human body, including the brain (speeds are very tiny relative to c, and actions are very large relative to Planck's constant h). They can be used to specify physical states or phenomena if those conditions are met (and at least implicitly stated in the argument).

    Secondly I would not like to see mass made fundamental to physicalism. In the standard model mass is a derived quantity (generated by the Higgs interaction and by the binding energy of gluons). Although mass in involved in some very interesting questions of broken symmetry (current work on neutrino masses comes to mind), it is not a reliable base to found a philosophic view upon. Energy (in the strict physical sense of the word) and momentum would be better for that purpose. But it would be instructive to read some of the physicists' answers to the Edge question "What do you believe that you cannot prove?" for further insights on this.
     
    Last edited: Jan 6, 2005
  17. Jan 6, 2005 #16

    Les Sleeth

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    I am in a hurry now, so I'll have to wait until tomorrow to think about all your comments. But just one point.

    The definition I gave using mass was meant to say that physicalness isn't just anything with mass, but it is also that which is derived from mass (i.e., which now might be massless) and that which is manifested by the effects of mass present (such as gravity). Where I'm coming from with that is, basically, the Big Bang. It seems to me that that's what the BB primarily did -- create mass -- and then everything has emerged from and been manifested by that.

    What do you think of my thinking :tongue2: in this respect?
     
  18. Jan 6, 2005 #17

    Les Sleeth

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    Yes, but you aren't defining physicalness. You are describing human perception. What I am after is the properties of physicalness itself which something must minimully possess to be recognized as physical.
     
  19. Jan 6, 2005 #18

    StatusX

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    We shouldn't just freeze physicalsim at what we know now (GR and the Standard Model), since, as SelfAdjoint pointed out, the definition of physicalism has changed as science has progressed. It seems you are trying to define physicalsim so that the things you believe to be unphysical, such as consciousness, remain so. I think "physical" should be defined from a social point of view: having the capacity to be investigated and explained by science. It seems pretty clear what is scientific and what isn't, and as science expands, so will the realm of the physical.
     
    Last edited: Jan 6, 2005
  20. Jan 6, 2005 #19
    Apologies for being repetitive, but I am defining physicalness; I am saying it is dependant upon human observation. I'm unwilling to replace the word "observation" with "perception" and do not understand why you did that. Observability is the most fundamental property of physical to me. When you ask if something is physical, that may very well be the only property I consider.

    I would disagree with Self Adjoints definition of physicality on the grounds that it is circular and temporary. Defining something as physical because we currently have a predictive system that can predict things about it to me seems backwards. We generated that system (GR or SM) by observing physical things. Using that system to then define what it is for something to be physical seems to me rather backwards. On top of that, we are almost certainly to make advances in physics that would require his definition to be rewritten for the new ideas.

    So why am I not giving you want you want? I don't feel particularly new to this conversation, but the responses to my posts seem to suggest - respectfully - that I'm somehow missing the point. I am more the willing to admit I may be doing that, but I just don't understand why or how.
     
  21. Jan 6, 2005 #20

    selfAdjoint

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    According to what is called the standard model of cosmology (not to be confused with the standard model of particle physics), immediately after the big bang there was no mass; the forces were all unified and the particles had not condensed out of the energy. In general relativity mass is only one of the sources of energy and momentum which warp spacetime; light, which has momentum but no mass, is another. Gravitational waves are still another.

    Paul Davies has a book called The Matter Myth which discusses some of these ideas.
     
  22. Jan 6, 2005 #21

    honestrosewater

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    Would a definition including observability and parsimony be acceptable?
    For instance, "an object is physical if it can be directly observed or postulated as the cause of an observable effect in a system where each physical effect has one and only one physical cause and direct observation is a physical effect," or something along those lines.
     
  23. Jan 6, 2005 #22

    loseyourname

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    But we didn't say "physical" meant "subject to relativity." We said it meant "subject to mathematical predictability." It still seems the only reason you don't like this is because you want a definition that excludes your conception of consciousness.

    To go with your bike analogy. It takes balance to ride a bike, but not all balancing acts are riding a bike. Works fine for riding a bike. But with the word "physical," all mathematically predictable phenomena are physical. This is not logically derived. It is just this way by definition. This might be the most succint definition I can give:

    Any phenomenon is physical if and only if it displays extrinsic relationships that can be mathematically modelled.
     
    Last edited: Jan 6, 2005
  24. Jan 6, 2005 #23
    I've long had a favorite definition of physicality. "Physical things are only those things which exert influence over some physical things." To put this into action you assume that some particular things are physical, such as basketballs, and everything which influences them is physical. Physicality by this definition is exactly what someone trying to predict some physical event must consider.

    Dualists like to say that physicality is more limited than this, because if the soul has any influence on the physical world, then the soul itself must be physical by this definition. Dualists generally say something that boils down to, "physical things are only those things which fall under (the previous definition of physicality) but are not of the spirit."

    I dislike this definition because according to it, physicists, in trying to predict things, must sometimes consider non-physical things.
     
    Last edited: Jan 6, 2005
  25. Jan 6, 2005 #24

    All these definitions are all well and good. They cause more confusion than they produce knowledge, if any. They cause more problems than they solve. Just imagine living in a world where everyone speaks one langauge and every word in the dictionary has only one meaning? Imagine what the world would look like. All these definitions that you have invoked from various sources reiterates and reinforces my earlier call in some of the threads on this PF for all these terms to be revised and given a commonly accepted definitions and connotations. 'MATTER' and 'PHYSICAL' are good examples of these terms. In terms of the notion of 'Physical', the very simplest and the most basic meaning of it is 'ANYTHING YOU CAN SEE'. The problem arises form limiting the meaning of the term 'SEE' to anything that we see with our eyes only. But supposing we extend the notion of see to include all the five senses?

    The questions that new generations of philosophers are now asking are these: what would happen to the whole system of the human perception if all the visual organs in a human body were scientifically reduced to one single visual organ? How would this be engineered into the body? And let's say this was possible in the first place, how would we see and interprete the world? Would we end up with a new reality? Ultemately, would the multi-partite self still exist?

    Ok, what about these?

    When you see with your eyes, are you seeing?
    When you hear with your ears, are you seeing?
    When you smell with your nose, are you seeing?
    When you feel with your skin, are you seeing?
    When you taste with your tongue, are you seeing?
    When you introspect, think or reason, are you seeing?


    And ultemately,

    When you use scientific instruments or any known visual aids or extensions, are you seeing?

    On the other hand, if the human still remained in its present state with its present multi-partite configuration, sooner or later we would have to come to a common definition and understanding of what it realy means for something to be physical. My own observation up to now is that we are mistaking our own visual limitations for something over and above the physical. We are failing to take our visual and sensual limitations into account of the problem. As I have observed everywhere in this forum, it seems that when something is beyond the range of the human observation, we give it a different name and think of it as being something else. The question that will continue to haunt our conscience for a very long time to come is this:

    If the human physical or material body extends beyond what we can see and fully explain, does it stop being physical from this point, given that we knew what the term 'physical' really stands for in the first place?
     
    Last edited: Jan 6, 2005
  26. Jan 8, 2005 #25

    FZ+

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    It's a little dangerous, though, as a definition since some physical events seems to disobey cause-and-effect. But it would be the definition I prefer too, so long as we include influences like altering probabilities, as well as direct stuff.
     
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