Evaluate the case for the necessity of origin thesis.
In order to answer the ongoing problem of transworld identity, that is to say, how identity can endure across possible worlds, various theories have been developed. Unsatisfied with the notion of a hacceity (the so-called ‘thisness’ of an object which must be a property that the object has in all possible worlds) due to its mysteriousness, metaphysicians have come up with theses that add to the necessity of identity. One of the propositions that attempts to answer transworld identity is the necessity of origin thesis. Put simply, the theory posits that if an object a originated from a certain source in the actual world, then any world in which a exists, a then originates from that same source. This theory seems naturally persuasive, but in this essay I hope to concede this theory doesn’t really bring us any closer to answering how an object’s identity can endure across possible worlds.
In order to discuss the theory’s validity, what it is actually saying must be clarified. To use an example from E. J. Lowe[1], if there is a tree T, and an acorn A, then if T exists, T must necessarily have originated from A. Lowe states that the obvious implication is that even if a similar acorn had been planted exactly where A was planted, the tree that grew would not have been T, therefore: any tree originating from A is T. It is important to note, however, that for Saul Kripke (1980), who first posited a version of the thesis, the necessity of an object has to its origin does not apply to its ensuing history, and that is where the distinction lies. For Kripke, in the example of a human being, it’s ‘source’ as such is its ‘biological antecedents’[2]. Kripke gives an example about the Queen of England, and one could easily imagine history unfolding in a possible world quite differently to how it did in the original world, but one can not easily imagine her being born from different parents, as how could a ‘person originating from different parents, from a totally different sperm and egg, be this very woman?’[3] This seems quite persuasive; however, both Lowe, Penelope Mackie[4] argue that although the intuitiveness of the thesis is undeniable, this does not mean it is defensible.
Starting with Lowe’s argument, it is necessary to first explain the four-world argument for the necessity of origin thesis, which Lowe goes on to conclude is somewhat absurd. Using the same example as before, he uses acorn A and tree T, and goes on to use a further acorn, B. He posits various worlds, using w0, w1… etc:
- w0: A = T. This is the actual world.
- w1: B = T1 = T. This is the second posited world, where we are maintaining even though the acorn is different, they are identical, as A does not exist in w1.
- w2: A = T2a
B = T2b
Here Lowe is positing a world where both acorns exist, growing into similar trees. It seems we should assume acorn T2a here is the more identical with T, as it came from the original acorn A.
- w3: No A.
B = T3
Here, there is a world with no acorn A, but an acorn B. Lowe’s problem with this is that then, there are two worlds, w1 and w3 which ‘differ from each other merely in respect of the identity of a certain object.’[5] The only way then to avoid this seemingly ridiculous position, is to accept the thesis of the necessity of origin. But Lowe has two persuasive objections to this: one is that he does not see why T2a OR T2b have to be identical with T at all. If we say neither are, then we can easily reject the thesis of the necessity of origin. Following on from this, his second objection is why T2a has to be any more likely to be identical with T than T2b. He thinks here we are just championing the certain respects T2a is similar to T, and ignoring the respects T2b may be similar. In conclusion to Lowe’s argument, he says it may well be a strong refutation of the four-worlds argument shown above that it ‘implicitly assumes precisely what it sets out to prove.’[6]
In Mackie’s book, she discusses the various theories that try to solve the gaps in the necessity of origin thesis, such as the ‘overlap requirement’ and the ‘sufficiency of origin’ thesis. For Mackie, it seems irrefutable that we normally have a propensity to assume a human being to keep hold of some properties when we consider how they could have been different, and even some of the unique properties that are related to its origin. So here, Mackie is agreeing with Kripke to a certain extent. She also thinks that we do give more weight to origins of an object than to the subsequent history that ensues. However, she thinks that trying to propose that these facts about our ‘de re modal intuitions can be enshrined in a defensible version of something as strong as the necessity of origin thesis does not… survive careful scrutiny.’[7]
Overall, although the intuitiveness of the thesis does seem undeniable for most philosophers studying and scrutinizing Kripke’s work, the strength of the claim just seems too much to be able to logically prove. Mackie posits the ‘tenacity of origin’ thesis as a much more obtainable conclusion, stating the origin of a subject is ‘normally kept fixed’[8], and nothing stronger than this. Lowe thinks that the thesis of the necessity of constitution is a more plausible one. However, with regards to the necessity of origin thesis, due to the thesis being too strong to accept, it does not answer the question of transworld identity at all adequately, as we cannot really demonstrate or prove it.
[1] Lowe, E. A Survey of Metaphysics (Oxford University Press, 2002).
[2] Kripke, S. Naming and Necessity (Blackwell, 1980) page 113.
[3] Kripke, S. Naming and Necessity, page 113.
[4] Mackie, P. How Things Might Have Been: Individuals, Kinds and Essential Properties, Section 6.
[5] Lowe, E. A Survey of Metaphysics, page 105.
[6] Lowe, E. A Survey of Metaphysics, page 105.
[7] Mackie, P. How Things Might Have Been: Individuals, Kinds and Essential Properties, Section 6.9
[8] Mackie, P. How Things Might Have Been: Individuals, Kinds and Essential Properties, Section 6.9
