No identity without agency

Boris Hennig

IFOMIS

Universität des Saarlandes

Postfach 15 11 50

66041 Saarbrücken

 

Abstract. The material constituents of the ship of Theseus are gradually replaced by new ones, but kept in some place. After everything has been replaced, from this material a new ship is built, which is similar in every detail you care to mention. It is even owned by Theseus. Which one of these ships is the ship of Theseus? This question can be given an alternative formulation: Which one of these ships is the one that Theseus used to sail to Crete?

I contend that the second version of the question has an obvious answer. It is the actions in which the ship is involved that yield the relevant criteria of identity. To repair a ship is to keep it in use; to build a copy of it is not. The ship, rather than a heap of planks, was used to sail to Crete. The planks were used to build another ship. This other ship was not used to sail to Crete.

The general idea of my approach is a broadly Cartesian one: in order to solve problems such as the "Ship of Theseus", we have to ask why it is important to identify and re-identify anything in the first place. I claim that the most important case of identification is also the clearest case: the identification of persons, insofar as they are responsible for actions. We need to identify persons in order to be able to count on them, expect future actions and sanction or encourage the repetition of past actions. We can ask them for explanations and justifications of what they did in the past.

In order to identify agents, we frequently also need to identify organisms, artefacts or other material things. The reason is that intentions, beliefs and expectations can be publicly identifiable only if such things as living human beings, written statements or video documentations are publicly identifiable.

 

The claim that the clearest possible case of identification is constituted by the ascription of actions to persons is an ontological, not merely an epistemological or pragmatist one. Persons are the most clear-cut things that exist. Organisms are the next best candidates for identification because they are still capable of a kind of autonomous agency, though not of justifying what they 'did' in the past.  Finally, artefacts are most naturally identified by reference to their use or design, which are again actions. Hence, there are good criteria for identifying and re-identifying agents and living organisms; there are fairly good such criteria for artefacts, and there are no reliable criteria for distinguishing and re-identifying arbitrary aggregates of matter (by their form).

When I claim that there is no identity without agency, I do not claim that every case of identification must involve the identification of an action. Rather, I claim that there would not be any use in identifying such entities as ships were it not for the purpose of ascribing actions to such entities as sailors. We can solve the "Ship of Theseus" problem by remembering the proper function of the concept of identity. If there were no need to identify agents, there would be no need to identify anything else. Hence, the question about the ship of Theseus will more likely be answerable when it is connected to a question about the identity of an agent, e.g. Theseus.