metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

, the multiple occupancy view (m.o.) is a particular analysis of fission cases, which claims to be at least ''

a priori ("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...

'' possible, if not actually true of real cases of fission.

Description

Imagine an

amoeba An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudo ...

which undergoes symmetrical

fission Fission, a splitting of something into two or more parts, may refer to: * Fission (biology), the division of a single entity into two or more parts and the regeneration of those parts into separate entities resembling the original * Nuclear fissio ...

into two sister amoebae (call them B and C). We tend to think that before fission there was one amoeba (call it A), but what has happened to it? It has not died, for death is a biological state, and there are no dead amoebae lying around after the fission! In fact, there is more life after the fission than there was before, i.e. two live amoebae instead of just one. Has A somehow ceased to exist without dying? Is A still around, and identical with either B or C? It cannot be identified with both B and C, for identity is a

transitive relation In mathematics, a relation on a set is transitive if, for all elements , , in , whenever relates to and to , then also relates to . Each partial order as well as each equivalence relation needs to be transitive. Definition A hom ...

, and B is certainly not the same amoeba as C. Yet, the fission was symmetrical, so neither B nor C has any more or less claim to be A than the other. This is the problem. We seem to be forced to say that A has ceased to exist, but the m.o. view provides us with another option, consistent with all of the above considerations. The m.o. view is that there were two distinct but coincident amoebae before fission, occupying the same body of matter, but which diverge upon fission into the same two distinct, but no longer coincident, amoebae. The number of amoebae hasn't increased, i.e. there were two before fission, and there are the same two after fission. The amoeba has "divided without multiplying"! The m.o. view has also been applied to hypothetical cases of symmetrical fission involving persons. On the face of it, the m.o. view contravenes the principle of

identity of indiscernibles The identity of indiscernibles is an ontological principle that states that there cannot be separate objects or entities that have all their properties in common. That is, entities ''x'' and ''y'' are identical if every predicate possessed by ' ...

. However, one and the same physical object can be a proper part of two or more distinct objects (e.g., a road intersection is part of two distinct roads), which leads to

four-dimensionalism In philosophy, four-dimensionalism (also known as the doctrine of temporal parts) is the ontological position that an object's persistence through time is like its extension through space. Thus, an object that exists in time has temporal parts ...

, whereby, for example, an amoeba at a time (amoeba stage) is a temporal part of an amoeba extended in time, i.e., objects have temporal parts.

References

* 2007: Multiple occupancy, identity, and what matters. ''Philosophical explorations'', 10(3): 211–225. * 1985: Can amoebae divide without multiplying? ''Australasian journal of philosophy'', 63(3): 299–319. Metaphysics {{metaphysics-stub