Our Knowledge of Sameness (2021 Version)

How ubiquitous, yet how strange, is sameness!  The strangeness of the ordinary. Sameness is a structure of reality so pervasive and fundamental that a world that did not exhibit it would be inconceivable. There is synchronic and diachronic sameness. I will be discussing the latter.

How do I know that the tree I now see in my backyard is numerically the same as the one I saw there yesterday? Alvin Plantinga (Warrant and Proper Function, Oxford 1993, p. 124) says in a Reidian vein that one knows this "by induction." I take him to mean that the tree I now see resembles very closely the one I saw yesterday in the same place and that I therefore inductively infer that they are numerically the same. Thus the resemblance in respect of a very large number of properties provides overwhelming evidence of their identity.

But this answer is open to objection. First of all, there is something instantaneous and immediate about my judgment of identity in a case like this: I don't compare the tree-perceived-yesterday, or rather my memory of the tree-perceived-yesterday, with the tree-perceived-today, property for property, to see how close they resemble in order to hazard the inference that they are identical. There is no 'hazarding' at all.  Phenomenologically, there is no comparison and no inference. I just see that they are the same. But this 'seeing' is of course not with the eyes. For sameness is not an empirically detectable property or relation. I am just immediately aware -- not mediately via inference -- that they are the same.  Greenness is empirically detectable, but sameness is not.

What is the nature of this immediate awareness given that we do not come to it by inductive inference or by literally seeing (with the eyes) the numerical sameness of yesterday's tree and today's tree?   And what exactly is the object of the awareness, identity itself?

A problem with Plantinga's answer is that it allows the possibility that the two objects are not strictly and numerically the same, but are merely exact duplicates or indiscernible twins. But I want to discuss this in terms of the problem of how we perceive or know or become aware of change.  Change  is linked to identity since for a thing to change is for one and the same thing to change. 

Let's consider alterational (as opposed to existential) change. A thing alters if and only if it has incompatible properties at different times.  Do we perceive alteration with the outer senses? A banana on my kitchen counter on Monday is yellow with a little green. On Wednesday the green is gone and the banana is wholly yellow. On Friday, a little brown is included in the color mix. We want to say that the banana, one and the same banana,  has objectively changed in respect of color.

But what justifies our saying this? Do we literally see, see with the eyes, that the banana has changed in color? That literal seeing would seem to require that I literally see that it is the same thing that has altered property-wise over the time period. But how do I know that it is numerically the same banana present on Monday, Wednesday, and Friday? How do I know that someone hasn't arranged things so that there are three different bananas, indiscernible except for color, that I perceive on the three different days? On that extraordinary arrangement I could not be said to be perceiving alterational change. To perceive alterational change one must perceive identity over time. For there is change only if one and the same thing has different properties at different times. But I do not perceive the identity over time of the banana.

I perceive a banana on Monday and a banana on Wednesday; but I do not visually perceive that these are numerically the same banana. For it is consistent with what I perceive that there be two very similar bananas, call them the Monday banana and the Wednesday banana.   I cannot tell from sense perception alone whether I am confronting numerically the same banana on two different occasions or two numerically different bananas on the two occasions. If you disagree with this, tell me what sameness looks like. Tell me how to empirically detect the property or relation of numerical sameness. Tell me what I have to look for.  Sameness is like existence: neither are empirically detectable features of things. 

Suppose I get wired up on methamphetamines and stare at the banana the whole week long. That still would not amount to the perception of alterational change. For it is consistent with what I sense-perceive that there be a series of momentary bananas coming in and out of existence so fast that I cannot tell that this is happening. (Think of what goes on when you go to the movies.) To perceive change, I must perceive diachronic identity, identity over time. I do not perceive the latter; so I do not perceive change. I don't know sameness by sense perception, and pace Plantinga I don't know it by induction. For no matter how close the resemblance between two objects, that is consistent with their being numerically distinct. And note that my judgment that the X I now perceive is the same as the X I perceived in the past has nothing tentative or shaky about it. I judge immediately and with assurance that it is the same tree, the same banana, the same car, the same woman. What then is the basis of this judgment? How do I know that this tree is the same as the one I saw in this spot yesterday? Or in the case of a moving object, how do I know that this girl who I now see on the street is the same as the one I saw a moment ago in the coffee house? Surely I don't know this by induction.

How then do I know it?  I don't for a second doubt that it is the same tree, the same banana, the same girl. I am strongly inclined to say that I know that it is the same tree, etc.  The question, however, is how I know it. How is it possible that I know such a thing given that transtemporal identity is not empirically detectable?  My inability to explain how it is possible would seem to some to cast doubt on my claim that I do know that it is the same tree, etc.  Others will demur and say that what is actual is possible whether or not one can explain how it is possible.  One simply waxes dogmatic in the face of critical raisonnement.

If I cannot know diachronic identity empirically, do I impose the concept of such identity on what I literally see so as to enforce the numerical identity of the two trees, the two bananas, the two girls?  Do I really want to say that identity is a transcendental concept to which nothing in the sensory manifold corresponds, a concept that I impose on the manifold?

Comments

[Chad Wooters]

Is this a question about warranted beliefs? Once one has given something an identity (and here I am assuming people have and use multiple hueristics [sp] to identify thing) when is there sufficient warrant to reconsider? Imagine a heist movie in which a famous painting is replaced by a near perfect forgery. Upon seeing a known theif milling about, a suspicious collector might try to reassure himself of the safety of the original by reexamining the work. In this case, sameness is assumed until there is warrant to consider otherwise. The issue arises only when there is a potential cause, like a theif, capable of effecting a change.

[John Paul]

Mr. Vallicella, I have been following your blog for about a month now and greatly enjoying it. I graduated with an undergrad degree in philosophy last spring and you have been helping me continue the life of the mind (and the life of meditation) while working in the trades.
May I offer a thought or two in answer to your provocative questions? I do not have any conclusive answers, just some thoughts worth considering. First, it seems possible to me that we do directly perceive change in one arena (though not necessarily with sense knowledge), namely in self awareness. I think therefore I am, and I think new thoughts therefore I change. Second, while I would certainly hesitate to make change a transcendental category, I do think that our awareness of change is intrinsically bound up with our ability to remember. While I do not consciously compare the properties of the remembered banana with the features of the current banana, my judgement “this is the same banana as the one I remember” is only possible because of memory. And, while it might be possible to partially fool someone in certain circumstances with constant annihilation and replacement with replicas, I find it hard to believe that would be possible with something like my experience of unity with my body. That experience is continuous in away which I think impossible to break up into discrete parts. Finally, I have always found interesting the thomistic thesis that the act of judgement corresponds to an aspect of reality which is not captured by concepts. If we cannot conceive how we judge that this tree is the same one across time, perhaps that is because our judgement is not reducible to a concept. One of the traditional properties of the “being” known by judgement is unity. Perhaps that includes unity across time.

As I said, merely food for thought. I don’t have any more answers than you do.

[BV]

Thank you for your friendly comment, Mr. Paul.

>> First, it seems possible to me that we do directly perceive change in one arena (though not necessarily with sense knowledge), namely in self awareness. I think therefore I am, and I think new thoughts therefore I change.<<

Indeed, the case of the self is very different from the case of a physical thing in the external world. How do I know that the tree is not a diachronic bundle of temporal parts with no underlying unity? I do seem to know that I am not such a transtemporal bundle.

Suppose I hear successively three separate notes of a simple melody. But now suppose for reductio that the acts of hearing occur in the same subject, but that this subject is not a unitary and self-same individual but just the dischronic bundle of these three acts, call them A1, A2, and A3. When A1 ceases, A2 begins, and when A2 ceases, A3 begins: they do not overlap. In which act is the hearing of the melody? A3 is the only likely candidate, but surely it cannot be a hearing of the melody. For the awareness of a melody involves the awareness of the (musical not temporal) intervals between the notes, and to apprehend these intervals there must be a retention (to use Husserl’s term) in the present act A3 of the past acts A2 and A1. Without this phenomenological presence of the past acts in the present act, there would be no awareness in the present of the melody. But this implies that the self cannot be a mere bundle of perceptions externally related to each other, but must be a peculiarly intimate unity of perceptions in which the present perception A3 includes the immediately past ones A2 and A1 as temporally past but also as phenomenologically present in the mode of retention. The fact that we hear melodies thus shows that there must be a self-same and unitary self through the period of time between the onset of the melody and its completion. This unitary self is neither identical to the sum or collection of A1, A2, and A3, nor is it identical to something wholly distinct from them. Nor of course is it identical to any one of them or any two of them. This unitary self is given whenever one hears a melody.

The unitary self is phenomenologically given, but not as a separate object. Herein, perhaps, resides the error of Hume and some Buddhists: they think that if there is a self, it must exist as a separate object of experience.