2. Persons, Persistence & Tuvix: What Makes Me “Me” From One Moment to the Next?
Jim Fahey
Rensselaer Polytechnic Institute
Philosophy Group – Department of Cognitive Science

3. METAPHYSICAL PRELUDE WHAT IS METAPHYSICS?
The study of WHAT THERE IS in the most general sense.
EXAMPLE:
A Metaphysical Distinction (from Aristotle)
SUBSTANCE (STUFF) = def., That which is Independent
ATTRIBUTE = def., That which is not substance

4. Kinds of Substance? What kinds of substance exist? Some Candidates:
Material
Mental (Spiritual)
Mathematical Entities
Space
Time

5. MIND-BODY PROBLEM 1. The (human) body is Material Stuff (substance).
2. The (human) mind is Mental (spiritual) Stuff.
3. Mind and Body causally interact.
4. Matter and Spirit DO NOT causally interact.

6. Some Basic Views on the Mind-Body Problem
MATERIALISM
(1), ~(2), (3), (4)
CARTESIAN
(INTERACTIONIST) DUALISM (Descartes)
(1), (2), (3), ~(4)

7. Some Basic Views on the Mind-Body Problem
IDEALISM
~(1), (2), (3), (4)
NON-INTERACTIONIST DUALISM
(1), (2), ~(3), (4)

8. What is the “I” TWO BASIC “SUBSTANCE VIEWS:”
Materialism – the “I” is a complex of material stuff;
Cartesian View – the “I” is unextended, thinking (mental) stuff.

9. The Problem of Persistence Through Change
But regardless of whether the “I” is MATERIAL STUFF as the Materialist contends or whether the “I” is MENTAL STUFF as the Cartesian avers, we must also be able to account for the fact that the “I” persists through change.
That is, PERSONS CHANGE OVER TIME BUT YET THEY REMAIN THE SAME PERSON.

10. I. A Metaphysical Starting Point For Discussions of Identity Through Time: Locke’s Principle of Identity
Locke believes that persisting things can remain “identical” from one moment to the next in accord with the following:
1. “One thing cannot have two beginnings of existence,
2. Nor two things one beginning” (II, 27,1)

11. II. A Basic Distinction Regarding Identity
TRUE IDENTITY is Numerical or Quantitative Identity and this refers to exactly one thing – In his discussion in II, 27, Locke is concerned with numerical identity.
But there is also a “loose and popular” use of the term ‘identity’ that means (very) similar and this can apply to two or more things. This is called Qualitative Identity.
To illustrate this distinction, consider the following:

13. Numerical (Quantitative) vs. Qualitative Identity
On the previous slide:
The shape directly to the left of the DIAMOND is NUMERICALLY IDENTICAL to the shape directly above the CIRCLE;
The shape directly above the CIRCLE is (merely) QUALITATIVELY IDENTICAL to the shape directly below the DIAMOND.

14. III. Locke’s View on Numerical Identity Through Time
We can divide Locke’s discussion of NUMERICAL IDENTITY THROUGH TIME into three levels:
a. same mass or heap (not particularly useful and hence we shall ignore it in what follows);
b. same living thing, or, more generally, same functional entity;
c. same person.

15. b. Same living thing (same functional entity)
We tend to accept that the vast majority of material things persist through time despite the fact that they often both lose and gain material parts. For these entities, being the same thing at t1 and t2 involves participating in a common “organization of parts in one coherent body” (II, 27, 4-6).

16. b. Same living thing (cont.)
For example, a tree can lose a branch and add new leaves. It remains the same tree at t1 and t2, however, as long as these “tree stages” participate in a “common life.”
It seems Locke is giving us an irreducibly “HISTORICAL ACCOUNT” of IDENTITY THROUGH TIME.

17. b. Same living thing (cont.)
Locke’s “historical account” applies to the “human animal” (same woman, same man) as well as other living organisms and, in general, all things that are what they are because of the structure/arrangement of their parts.
The living human animal comes into existence, gains and loses material parts and remains numerically identical from one moment to the next as long as each of those “woman (or man) stages” shares the same “beginning of existence” and participates in a “common history.”
So does a house …

18. Same Functional Entity

19. c. Same Person
But, for Locke, human animals (women, men) ARE NOT PERSONS. Indeed, Locke does not believe that any account of persons can be given in terms of a coherent history of substance.
That is, Locke‘s major contribution to discussions of personal identity is his offering of a “NON-STUFF” account of PERSON.
But to better understand Locke’s account, we should reconsider the standard “STUFF” accounts of PERSON.

20. Same Person (cont.) – MATERIALISM
SAME PERSON = SAME (functioning) (at t1 and t2) HUMAN BODY (at t1 and t2)
The Materialist may well agree with Locke that being the same tree at t1 and t2 involves participating in a common “organization of [material] parts in one coherent body.” But, these materialists also argue, such an account applies to PERSONS as well.

21. c. Same Person – Materialism (cont.)
To make this a bit more complicated, here are THREE VARIETIES OF MATERIALISM -- that is, three different ways of interpreting = SAME (functioning) HUMAN BODY (at t1 and t2)
The Brain Materialist holds that personhood depends on a functioning human brain and hence
SAME PERSON = SAME (functioning) (at t1 and t2) HUMAN BRAIN (at t1 and t2)

22. c. Same Person – Materialism (cont.)
The Whole-Body Materialist denies that the brain is any more important than any other similarly sized portion of the body and hence they take = SAME (functioning) HUMAN BODY (at t1 and t2)
at face value. Any reasonable portion of a human body -- including the brain -- can be replaced by a functionally similar part and if that body continues to function, it remains numerically identical.

23. c. Same Person – Materialism (cont.)
The Situated-Body Materialist goes beyond the whole-body materialist and argues that in order to have the = SAME (functioning) HUMAN BODY (at t1 and t2) we must consider not only the successive states of the whole material body, but also the general environment in which those successive states of material body are situated. So, just as a radical change in body could destroy identity, so too could a radical change in the body’s environment.

24. Same Person (cont.) CARTESIAN VIEW
SAME PERSON = SAME MENTAL (at t1 and t2) STUFF (at t1 and t2)
Descartes holds that the “I” is unextended, thinking substance. Thus, being the same PERSON at t1 and t2 requires the presence of the same thinking substance.

25. Same Person (cont.) LOCKE’S VIEW
Locke argues that PERSONS are distinct from mere animals. And unlike chairs, trees, animals and the like, PERSONS are distinct from any kind of organization of either material or mental STUFF parts.
Instead, a PERSON is a self-conscious entity that bears at every stage of its existence a certain coherent collection of experiences -- thoughts, feelings, memories and the like.
Thus Locke offers a MEMORY THEORY OF PERSONAL IDENTITY THROUGH TIME.

26. Same Person (cont.) -- More on Locke’s view
For Locke, PERSONS are forensic entities. That is, the essence of persons is that they are responsible agents bearing rights. On Locke’s view, PERSONS are self-conscious agents who are morally obligated to choose to perform only actions that respect the rights of others. As regards other persons, it would seem reasonable to hold that chief among the rights that PERSONS must respect is their RIGHT TO LIFE.

27. Same Person (cont.) – More on Locke’s view
Being the same PERSON at t1 and t2 involves having the “same memories.”
Note, however, that Locke is well aware that one can gain and lose memories over time. But, analogous to Locke’s tree example, if the PERSON at t1 and t2 each participate in one coherent corpus of memories, they are identical.

29. Personal Identity Through Time: The “Replacement (Ship of Theseus) Problem”
The planks of Theseus’ Ship are replaced one at a time. Each time a plank is replaced the ship remains the same since it is only “one plank different.” But what do we say about the case where all the planks have been replaced?
The Plank Hoarder Problem …

30. House of Theseus

31. Personal Identity Through Time: The “Splitting-Merging Problem”
Part 2 of Locke’s Principle of Identity through time says that “two things cannot have one beginning.” But Locke was unaware of such things as “cellular mitosis” where one thing gives rise to two things. More generally, what if persons split?

33. Personal Identity Through Time: The “Splitting-Merging Problem” (cont
Note that in the previous slide we have suggested an analogy between the traditional metaphysical views of SUBSTANCE & ATTRIBUTE and the modern-day computer science distinction between HARDWARE & SOFTWARE.
Materialists and Cartesians focus on SUBSTANCE (Stuff) and thus the respective views of PERSONS they espouse are HARDWARE views.
Locke’s Memory Theory unpacks the essence of PERSONS in terms of ATTRIBUTES and thus provides a SOFTWARE view of PERSONS.

34. Personal Identity Through Time: The “Splitting-Merging Problem” (cont.)

35. Personal Identity Through Time: The “Splitting-Merging Problem” (cont.)
Tuvok and Neelix, members of Captain Janeway’s crew on the Starship Voyager, suffer a “transporter accident” and are seemingly merged into one being, TUVIX.
Captain Janeway orders the process reversed but it seems that this will “do away with” Tuvix.
Is she performing a RIGHT ACTION in ending Tuvix’s life? Doesn’t Tuvix have a right to life?

36. Personal Identity Through Time: The “Splitting-Merging Problem” (cont.)

37. Ethics: The Big Guy in the Cave

38. Ethics: Some Basics
CONSEQUENTIALIST VIEWS: Actions are right or wrong depending on the consequences they produce. Among the most popular of consequentialist theories is UTILITARIANISM which holds (roughly) that a right action is one that produces the greatest balance of pleasure over pain.

39. Ethics: Some Basics (cont.)
DEONTOLOGICAL VIEWS: Actions are right or wrong in and of themselves. That is, they are right or wrong independent of any consequences they produce. Among the most popular of deontological theories is KANTIANISM which holds that right actions NEVER treat persons merely as a means but always as an end in themselves. On a Kantian view, it is always wrong to kill an innocent person since to do so is to treat him/her merely as a means.

40. Personal Identity Through Time: The “Splitting-Merging Problem”

41. Personal Identity Through Time: The “Splitting-Merging Problem”