Identity through Time
With respect to material objects, a thing remains the same if and only if its four causes remain the same. But given even the slightest change even in one of the causes, the old thing corrupts and a new thing is generated.
Thus, you can’t bathe in the same river twice, because, though the river’s form remain the same, its matter (water) changes; nor in the same water twice, because though the matter persists, the water’s form changes into a different river. But if we consider the form only, then you can bathe in the same river more than once; and if we consider matter only, then you can bathe in the same water more than once, if you run fast enough to where the old water has ended up.
The Theseus’s ship does not persist upon even a single new plank’s being installed. Matter must be numerically rather than merely qualitatively the same for identity to hold, so even if the new planks are made of the same kind of wood, there is no identity. (An argument can be made that two pieces of lumber qua matter are practically indiscernible. But they are not thereby made identical. So, it still matters whether the plank is old or new.) But if a new ship of the same form as the old one is made out of the old wooden planks (e.g., it follows the old ship and picks up the old planks which are thrown overboard), then given also the same efficient and final causes, that ship is identical to the old ship, while the renewed old ship is not.
With respect to human personal identity we must pay attention not only to the essence of a person, as defined by the four causes, but also to his self-knowledge and self-love. One’s personality cannot change very quickly, because any change must be “approved” (loved) and tracked and the resulting new person known. Update. In other words, even though in the strict sense I am not identical to the person “I” was yesterday, in a fast and loose sense I am (just as in such a sense a ship with just one plank replaced is identical to the old ship), but the identity is contingent on small changes accompanied by corresponding alterations in self-knowledge and self-love.
Update 2. There is a certain amount of permanence in a human being enshrined in the distinction between nature and nurture. Some qualities, such as one’s temperament, do not change, while others do. This further serves to perpetuate the illusion of a persisting identity through time.
July 28th, 2008 at 3:14 pm
What if material objects’ identity was grounded in form? Do you think this would lead to a conceptualist thesis that grounds the identity of some material object in a mind as it’s ideal concept?
July 28th, 2008 at 3:46 pm
You can always abstract “bottle-ness” from this bottle and that bottle and say that the former exists in the mind. Now a real human being is more than his humanity: it also includes this flesh, these bones, this personality. Similarly, a real bottle is more than bottle-ness, because it also is made from this glass, by this artisan (creating efficient cause), sustained by these physical forces (sustaining efficient cause), for this purpose. My claim is that a material object strictly speaking is a conjunction of the Aristotelian four causes of it. (Can you think of a counterexample?)
July 28th, 2008 at 4:51 pm
Dense: Aquinas’ De Ente et Essentia. I’m not sure about the translation, but at least it’s English.
July 28th, 2008 at 5:06 pm
My thought is that absent the conceptual or personal realm which intuitively captures formal and final causes, physical objects can have no identity through change whatsoever. The only way out of this is to analyze formal causes as platonic entities, but apart from a conceptualist thesis, this option isn’t very informative and runs into other epistemological (the possibility of knowledge of them) and metaphysical (the possibility of an actual infinite number of them) objections.
July 28th, 2008 at 5:41 pm
OK, suppose there is such a realm. How does it help a physical object preserve identity through change? If you want to ground identity in form only, then wouldn’t the forms exist immanent in things even without minds? Information on what a thing is — the form — can be out there, yet unaccessed by anybody, can’t it?
July 30th, 2008 at 12:30 am
Well, what you would need is an immanent mind.