Friday, June 09, 2017

Substitutivity

I'll comment on Tuggy's attempted reply to me:


I'd like to single out this particular line of argument:

Generally, when Hays, in interacting with me, starts riffing on the metaphysics of time or personal identity, it is because he wants to deny this:Things which differ are two (i.e. are not numerically identical)
which is premise 2 in this argument, an argument to which McClatchie and Hays seem to lack any good reply. To put it differently, nothing can, either at one time or in eternity, be and not be some way. Ridiculously, Hays denies this. Why? Because his confused, pop-evangelical theology says that Jesus just is God and vice-versa. And yet all Christians think, on scriptural grounds, that God and Jesus have differed. So this self-evident truth, Hays reasons, has got to go!
Epistemically, this is indefensible. The above principle is just as evident to Hays as it is to me. It has the same epistemic status as countless other principles he’d insist on, like the validity of modus ponens. He employs it all the time without realizing it. It’s probably unfortunate for him that he heard it from me. If he’d heard it from someone on his theological team, his head would immediately nob. “Yes, that is obvious.”But coming from me, it just must be the product of some ungodly speculations. It must be, ’cause it helps to make a problem for my obviously-correct theology!
Well, no, it’s not. Basically every one of these worked out Trinity theories is designed to be consistent with the indiscernibility of identicals. That’s because these philosophers (with the exception of the logically idiosyncratic Geach) see that it is self-evident that if some x and some y actually differ (or have differed, or will differ, or even just could differ) that it is false that x = y. Understanding this is just part of understanding our concept of (numerical) identity. Many times, a philosopher will explain identity as that relation whichnecessarily: is reflexive, transitive, and symmetrical, and which forces absolute indiscernibility.

1. Let's compare that to a recent exchange that Tuggy and I had on my blog:

Tuggy
In the NT, 'the Son' and 'Jesus' are co-referring terms. That is to say, it is assumed that Jesus just is the Son, and vice-versa. In plain English, these are not two characters, but one. You just asserted that one existed before the other; but that requires them to be two."

Hays
Norma Jeane and Marilyn Monroe are coreferring terms. Does that mean Norma Jeane was always a movie star, Playboy centerfold, wife of Arthur Miller and Joe DiMagio? Things can be true of the same individual at one stage of life, but false at another stage of life. 

Tuggy then admits that my example "is obviously true". But obviously true in reference to what? The reality of change, or the indiscernibility of identicals? 

Continuing the exchange:

Hays
That's why your invocation of is the indiscernibility of identicals is arbitrary. You yourself make that consistent with change. But in that event, you're not using the the indiscernibility of identicals as your standard of comparison. Rather, you are using your theory of personal identity as your standard of comparison, and then adapting the indiscernibility of identicals to accommodate the reality of change in reference to the same individual. So you're very flexible in how you apply the indiscernibility of identicals in that case, but very inflexible in how you apply to the Trinity or the Incarnation.

Tuggy
We know that things change.

Hays
True, but what this means is that you're not using the indiscernibility of identicals as your standard of comparison. Rather, you begin with the experience of time as your standard of comparison. You then reformulate the indiscernibility of identicals to accommodate the experience of time.

Time is change. Change is difference. How is that consistent with the the indiscernibility of identicals? Not consistent if you absolutize the indiscernibility of identicals.

You're not using a necessary truth (indiscernibility of identicals) as your criterion. Just the opposite: your using a contingent truth (the experience of change) as your criterion. So you prioritize truths of fact over truths of reason. 

2. Compare Dale's methodology to John McTaggart. McTaggart denied the reality of time, based on the very same principles that Tuggy invokes: the dissimilarity of the diverse (i.e. identity of indiscernible) and the diversity of the dissimilar (indiscernibility of identicals).

Unlike Tuggy, he actually begins with that "self-evident" truth of reason, which he applies with ruthless, fanatical consistency. By contrast,  Tuggy approaches the issue from the opposite end of the spectrum. Tuggy begins with the self-evident truth of time. 

So there's a choice of starting-points. Do we, like McTaggart, take a necessary truth like the law of identity as our standard of comparison, and then disallow change because that conflicts with the law of identity? Or do we take a contingent truth like the experience of time, and allow that to qualify the law of identity? 

The same issue crops up in the case of transworld identity. On the one hand, it seems natural for us to make counterfactual claims. For instance, if I had a brother, I'd be somewhat different than if I didn't have a brother, or vice versa. For one thing, some of my memories would be different, and memories are an element of personal identity. 

But how can I be the same individual if something about me is different, especially something as significant as personal memories? So what gives? Do we deny the truth-value of counterfactuals? Or do we qualify the law of identity?

One move is to distinguish between intrinsic and extrinsic properties. I don't object to that distinction, but that's drawn in spite of the indiscernibility of identicals. 

Tuggy's dilemma is that he careens between two divergent "self-evident" principles. He absolutizes the law of identity when attacking the Trinity and the Incarnation, but he makes exceptions when the topic is diachronic identity or transworld identity. He exempts them from his strictures. So Tuggy's appeal is selective and arbitrary. 

3. Finally, let's take a comparison. Do symmetries satisfy the principle of substitutivity (i.e. indiscernibility of identicals)? What makes them symmetrical is one-to-one correspondence. That's a rigorous criterion. 

But consider mirror symmetries. What makes them symmetrical is that you can place them in a relation of one-to-one correspondence.

Yet because they have the property of chirality, they are nonsuperimposable. Left-handedness is not interchangeable with right-handedness. 

So that's where Tuggy's false dichotomy between strict identity and strict alterity breaks down. Not everything is reducible to his binaries. 

2 comments:

  1. Steve, the post is just a confused charge that I'm somehow being arbitrary. It's all in your head, though. I apply ind id as I've explained it to every subject-matter, and I claim there are no exceptions, not even merely possible exceptions to it, since it is a necessary truth. This is what I've always said.

    My methodology, which you seem befuddled over, is Reidian. In brief, I think we must give some preference for theses such that every human seems built to know them. A more Leibnizian or Spinozist approach, like McTaggart's, is willing to throw common sense to the wind, and so we get absurd claims that there is only one thing (Spinoza), that no created things or events are related as cause-effect (Leibniz), or time is unreal (McTaggart). As many Christian philosophers have held, we need to consider common sense (or what Plantinga calls properly basic beliefs) to be, as it were, the voice of God to us, because it was he who build us this way. They seem to be the guideposts that he's given us. You seem to think I need some one theoretical starting point, but no, I deny that anyone ever does.

    In any case, I make no exceptions to *my* principle - no, not for diacrhronic identity. No, not for so-called "trans-world" identity. If what you mean by Ind Id doesn't mention the same time (or eternity), then I think it is false.

    This is disputed, by in my (and Aristotle's) view, change (as opposed to replacement, i.e. quick annihilation and then generation of something similar) logically presupposes the numerical identity of the before thing with the after thing. You know that you exist through time, and that you change, and so you know, without necessarily have any theory of personal identity, that change is real.

    But you also *know* *my* Ind Id. e.g. Bill Clinton likes fries. Her friend "Bill" has never liked fries. Ergo, Bill Clinton is not her friend "Bill."

    No, not a universal principle of substitutivity, which I have long thought false. e.g. Superman is so-called because of his powers. Clark Kent = Superman, Ergo Clark Kent is so-called because of his powers. That busts what you mean by Ind Id, but not what I mean by Ind Id. Do you see why?

    Keep searching, if you enjoy the hobby, for how, somehow, I'm claiming something speculative in all of this. But I'm actually very skeptical about metaphysical speculations, and I'm down on building them into theology. You'd better spend your time re-considering your own theological speculations. I didn't form my views on identity, etc. because I was looking to somehow "get" the Trinity or Incarnation. My philosophical views were pretty settled when I finally got to look into these matters. I was a card-carrying trinitarian through the first 12 years or so of my philosophical development. And as I've pointed out, philosophically trained trinitarians build their Trinity theories to not cause identity problems. You ought to follow their lead, and not kick against the goads. Get your theological house in order, instead of trying to play the metaphysician. Honestly, it's not your forte.

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    Replies
    1. "I apply ind id as I've explained it to every subject-matter, and I claim there are no exceptions, not even merely possible exceptions to it, since it is a necessary truth."

      But for you, the force of ind id is circumscribed by contingent truths about time and change.

      "My methodology, which you seem befuddled over, is Reidian. In brief, I think we must give some preference for theses such that every human seems built to know them." A more Leibnizian or Spinozist approach, like McTaggart's, is willing to throw common sense to the wind, and so we get absurd claims that there is only one thing (Spinoza), that no created things or events are related as cause-effect (Leibniz), or time is unreal (McTaggart)."

      But the reason McTaggart throws common sense to the wind is because he's more consistent than you are, whereas your own position is ad hoc. He begins with his a priori notion of ind id. And he refuses to let truths of fact (time and change) qualify the force of ind id.

      You, by contrast, allow for the same individual to have different properties at different times or have different properties in different possible worlds. How is that consistent with the law of identity? You can try to distinguish between intrinsic and extrinsic properties, but that's despite the ind id.

      "As many Christian philosophers have held, we need to consider common sense (or what Plantinga calls properly basic beliefs) to be, as it were, the voice of God to us, because it was he who build us this way. They seem to be the guideposts that he's given us."

      Which does nothing to reconcile the conceptual issue.

      "You seem to think I need some one theoretical starting point, but no, I deny that anyone ever does."

      An allegation that reflects your conceptual confusion. No, the question is not having only one starting-point, whether theoretical or pre-theoretical, but having consistent criteria.

      "You know that you exist through time, and that you change, and so you know, without necessarily have any theory of personal identity, that change is real."

      And what's the relationship between that a posteriori datum and ind id? Change is difference. Temporal difference. How is that consistent with strict identity?

      "Get your theological house in order, instead of trying to play the metaphysician. Honestly, it's not your forte."

      McTaggart was a far more eminent metaphysician than you will ever be.

      Moreover, philosophers do struggle over how change and counterfactuals are consistent with ind id.

      How is temporal or counterfactual differentiation compatible with ind id but Trinitarian differentiation is incompatible with ind id?

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