Multiple Realization Vs. Multiple Instantiation

Recently I have been having a very interesting discussion with Ken about his and Carl’s views on Multiple Realization. On thing that has come up is the distinction between multiple realization and multiple instantiation. Here is what Ken says about the distinction

you want to distinguish between multiple realization and multiple instantiation.  The former basically requires different lower level properties together realizing higher level properties, the latter basically requires different individual bearers of properties.  Take a molecule of type A and a molecule of type B, each having the same mass.  They will not multiply realize heat if they have the same kvelocity, since in both the mass and velocity are the same.  They will have different underlying individuals, although the same realizing properties.  Multiple realization involve multiplicity of realizing properties, not multiplicity in the kinds of individuals.
I have been trying to make trouble for Ken and Carl by arguing that almost any putative case of MR can be seen as a case of MI. A propos this purpose I was reading a very interesting news blurb on the invention of an artifical plastic blood. Is this an MR of blood or an MI of blood? I think it is an MI…what say ye, Brains readers?

BTW, I can’t resist linking to Chase Wrenn’s Conditional Material post on the realization relation where he responds to Carl’s objection from the SSPP for those that are interested…


  1. Carl Gillett

    Hi Richard, first thanks for posting the link to Chase’s post, I didn’t know about it and I shall post over there in due course. And thanks also for the link to the artifical blood. I have to go read about the details of the molecules, and their constituents atoms, as well as the roles of their respective properties, to see whether it is a case of MR or not.

    Second, I am lost about this worry about whether cases are just examples of multiple instantiation, rather than multiple realization. Some background issue must be operating that I am missing, since I really don’t see how to mix these two up. So let me respond and then you can tell me what I am missing.

    We taken realization to be a relation between property instances, usually with many lower level property instances together realizing a higher level property instance. Ken has laid-out some of the details, and I have a fuller account of realization that discharges the “in virtue of”, but the thumb-nail account that we use is basically this: Certain property instances P1-Pn in individuals S1-Sn realize some other property instance H in an individual S*, under some background condition, just in case S* has the powers individutive of H in virtue of the powers contributed by P1-Pn to S1-Sn, but not vice versa. There are further nuances we include, but this will do for here.

    Obviously, one can have many, many instantiations of the same higher level property instance: teeth have the property of having a certain hardness, so do palladium alloy fillings, and certain dental tools, and many other individuals. That is a case of multiple instantiation of a higher level property by many higher level individuals of different kinds.

    There is more to multiple realization, since it usually involves the property instances of lower level individuals as realizers of the instances of the relevant higher level property had by higher level individuals.

    Consider: (i) The bonding and alignment relations holding between atoms/molecules of palladium alloy, and (ii) The bonding and alignment relations holding between the atoms/molecules found in enamel. Each of (i) and (ii), though obviously instance sof very different properties, realize instances of the property of having a specific Knoop hardness — call this property H. The properties and relations in (i) realize an instance of H instantiated in metal fillings; whilst the properies and relations in (ii) realize an instance of H in uneteched human or bovine teeth. This is counted as a paradigm case of multiple realization under our view and we think that is just right.

    Note that this case, like many cases of multiple realization, does involve multiple instantiation of the higher level property – instances of a certain hardness are had by both teeth and fillings.

    Do you think this case is just one of multiple instantiation? And, if so, why isn’t it a case of the realization of instance of the same property by distinct lower level instances?

  2. Ken

    I’m visiting my family in Louisville this week, so I may be slower in responding. To determine whether this is MR or MI, I will have to look at the details of the case. Alas, it’s a bit hard to track down the original sources for this.

  3. Ken

    Ok. I’ve read the following sketch of what this artificial blood is like. Basically, you replace the amino acid chains of natural hemoglobin with a hyperbranched polymer (HBP), e.g. a polymer of 3-5 diacetobenzoic acid. That much is clear.

    In what follows, I want to set aside the fact that these particular molecules are not water soluble, hence cannot be inserted into erythrocytes without catastrophic effects. That adds complications regarding the background conditions $.

    Now suppose that both the amino acid chains and the HBP have the property of preventing heme deactivation. (See early part of discussion in link for this.) The property of preventing heme deactivation would be MR, since in amino acids there would be one collection of atoms with properties F1-Fn acting together to prevent heme deactivation and in the HBP there would be another collection of different atoms with properties F*1-F*m acting together to prevent heme deactivation. That seems pretty clear.

    Now, if the amino acid chains realize blood, it would seem that the HBPs also realize blood. Again, they amino acid chains and the HBPs do this in virtue of different properties F1-Fn borne by different individuals, so this would be MR of blood at the chemical level.

    Now the heme group in natural blood is the same as the heme group in the artificial blood (it appears). So, the heme would be univocally realized in natural and in this artificial blood, although multiply instantiated.

    Notice that, although the heme is presumably part of the chemical level realizer of blood, and is the same in both the natural and artificial blood, it is the different realizations of the property of being blood in the non-heme part that makes for MR at the chemical level.

    But, recall the realization is indexed to levels according to us.

    At a higher level, therefore, it could be that you analyze blood at a level in which there is a property of an oxygen binder and a deactivation preventer. And perhaps at that level, all blood is the same. Then you might have univocal realization at that level. On this score, the science appears to be less clear.

  4. Richard Brown

    Hi Carl, thanks for the very nice response! Ken, yours is also characteristically very informative as well…I must admit that I will have to think about this a bit further…I may have to admit that you guys are right…but let me try to resist a bit further and see what happens.

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