Personal identity

9th November 2020

Introduction to the topic: Introduction of The Mind’s I, by Daniel Dennet

Starting questions:

  • What is personal identity?
  • What defines me as an individual?
  • What is the essential property that makes me me?
  • What is the ‘thing’ that preserves my identity through time and through all the changes that come with it?
  • If I clone myself, will my clone have my same memories?

Abbreviations and terminology

  • PTPI: Psychological Theory of Personal Identity
  • MTPI: Metaphysical Theory of Personal Identity

Cartesian approach

The most immediate solution is a Cartesian one: I have an immortal soul that persists through all the changes that effect my body.

The same goes for all the traditional philosophy, since Plato up to Christian philosophy.

In addition, Leibniz points out preserving the soul isn't enough, it’s necessary to preserve memory. Descartes’ thought isn’t affected by this, in his philosophy it's impossible that a soul loses its memory because it's **constantly thinking** and it's always active.

Essentially, until I stop being (thus stop thinking), I’ll be the same “I” throughout my life.

Nevertheless, from a non-dualist point of view, the argument becomes tricky: does me living always in the same body means that I’m always the same?

A Materialist approach

(Note: all materialists are physicalists, while not all physicalists are materialists)

  • How do physicalists solve the problem of personal identity?
  • So does identity lies in my physical body?

The paradox of The Ship of Theseus:

The ship wherein Theseus and the youth of Athens returned had dirty oars and was preserved by the Athenians down even to the time of Demetrus palerus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers, for the logical question as to things that grow; one side holding that the ship remained the same, and the other contending it was not the same


if some men had kept the old planks as they were taken out, and by afterwards putting them together in the same order, had again made a ship of them, this without doubt, had also been the same numerical ship with that which was in the beginning; and so there would have been two ships numerically the same, which is absurd

Thomas Hobbes, De Corpore, ch. 11, §7

From a certain point of view, Hobbes can be thought as the first computational functionalist: to think is nothing than to think.

10th November 2020

The body swapping thought experiment

Another paradox is proposed by Bernard Williams in the paper The Self and the Future.

In brief:
The entire content of the brain, such as memories, intellect, consciousness etc. will be swapped in the bodies of two different people. Prior to the swap, to each of them will be submitted the following question:
“one of these two bodies will get a thousands of dollars, while the other one will be tortured, which one you choose to be tortured?”

Commonly, people opts for the money.

Note: there’s a difference between real possibilities and logical possibilities.

Lockean interpretation

The interpretation of personal identity by John Locke is explained in §19 and §20 of the second Essay on Human Understanding

P.I. persists over time because the individual retains memories of him/herself a different point of his/her life and each of those memories is connected to the ones before it.
We are our history and our memories: we are who we think we are.


A critique by Thomas Reid

Suppose a brave officer to have been flogged when a boy at school, for robbing an orchard, to have taken a standard from the enemy in his first campaign, and to have been made a general in advanced life. Suppose also, which must be admitted to be possible, that, when he took the standard, he was conscious of his having been flogged at school, and that when made a general he was conscious of his taking the standard, but had absolutely lost the consciousness of his flogging. These things being supposed, it follows, from Mr. Locke’s doctrine, that he who was flogged at school is the same person who took the standard, and that he who took the standard is the same person who was made a general. Whence it follows, if there be any truth in logic, that the general is the same person with him who was flogged at school. But the general’s consciousness does not reach so far back as his flogging—therefore, according to Mr. Locke’s doctrine, he is not the person who was flogged. Therefore, the general is, and at the same time is not the same person with him who was flogged at school

Reid, Essays on the Intellectual Powers of Man, III, 6

According to Reid, psychological continuity depends on metaphysical continuity and not vice-versa. This is very similar to what Descartes states.

Only a spiritual substance can preserve one’s identity: psychological continuity is possible only if there is an underlying metaphysical continuity.

A substance which stays the same regardless of psychological changes has to be found.

Williams’ second thought experiment

In short:
You became the test subject of a cruel scientist who informs you that he’s going to torture you. However, he anticipates something of what he’s going to do to reassure you. The following are his anticipations:

  1. at the time of being tortured, you’ll not remember being told you were to be tortured;
  2. at the time of being tortured, you’ll have no memories;
  3. at the time of being tortured, you’ll have no memories and you’ll have a whole different set of memories from a different person;
  4. the memories of that other person are memories of a person which is currently alive and his/her thoughts will be copied in your brain.

Which of the statements above reassure you?

Commonly, none


The main conclusion we can get from Williams’ experiments is that speaking of personal identity is a tricky reasoning.


11th November 2020

Hume on personal identity

Hume’s interpretation of personal identity, far from Locke’s one, can be found in Section VI of the Treatise of Human Nature

For from what impression cou’d this idea [the idea of self] be deriv’d? This question ’tis impossible to answer without a manifest contradiction and absurdity; and yet ’tis a question, which must necessarily be answer’d, if we wou’d have the idea of self pass for clear and intelligible. It must be some one impression, that gives rise to every real idea. But self or person is not any one impression, but that to which our several impressions and ideas are suppos’d to have a reference. If any impression gives rise to the idea of self, that impression must continue invariably the same, thro’ the whole course of our lives; since self is suppos’d to exist after that manner. But there is no impression constant and invariable. Pain and pleasure, grief and joy, passions and sensations succeed each other, and never all exist at the same time. It cannot, therefore, be from any of these impressions, or from any other, that the idea of self is deriv’d; and consequently there is no such idea.

With “some philosophers” Hume clearly refers to Locke. We can’t clearly know the substance In the first 38 lines of the Treatise on Human Nature, Hume already brings attention to his main point on the topic:
He uses experience in order to prove the idea that we aren't always conscious of ourselves. Experience doesn’t explain the individual’s perception of self. If we had an idea of the self, we should have experienced an impression of this.

Then, may we have an impression of self?
Self can’t be an impression. If the self actually is the same from birth to death, and if the idea of the self stays the same, we should have the same impression of it all along our lives.

Hume questions exactly this point. , which is … +++ … We don’t have an impression of the self

Again, Hume uses his experience to explain his confutation:

For my part, when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or plea- sure. I never can catch myself at any time without a perception, and never can observe any thing but the perception. When my perceptions are remov’d for any time, as by sound sleep; so long am I insensible of myself, and may truly be said not to exist. And were all my perceptions remov’d by death, and cou’d I neither think, nor feel, nor see, nor love, nor hate after the dissolution of my body, I shou’d be entirely annihilated, nor do I conceive what is farther requisite to make me a perfect non-entity.

We always have some perceptions, but they’re several and different, continuously varying over time.

Our self is a bundle of experiences collected during life:

The mind is a kind of theatre, where several perceptions successively make their appearance; pass, re-pass, glide away, and mingle in an infinite variety of postures and situations. There is properly no simplicity in it at one time, nor identity in different; whatever natural propension we may have to imagine that simplicity and identity. The comparison of the theatre must not mislead us. They are the successive perceptions only, that constitute the mind; nor have we the most distant notion of the place, where these scenes are represented, or of the materials, of which it is compos’d.


After writing The Treaties on Human Nature, which had very little success, Hume started to write essays.


We can find the idea of identity by analyzing the contrary idea of diversity: we have many different impressions and one succeeds another, and we confuse succession with identity.

Teleological, teleology: from telos, aim, scope.

An organism which has every part connected to the other.

16th November 2020


According to Locke we have no direct understanding of the mind, which is a complex set of different qualities and powers. These are connected by a substratum he calls we know not that.

It’s precisely because we don’t know if a spiritual substance actually exists that we need to theorize personal identity.

According to Hume, it can’t be known if a spiritual substance exists, and we don’t have enough elements to prove its existence.

The notion of “tabula rasa” is an epistemological question, not a metaphysical one, unrelated to the question of personal identity.

From Locke’s point of view, the question of personal identity is more of a legal problem than a metaphysical one, it’s connected to the domain of law. Locke is the first to address this issue with modern terms placing it in the context of morality and law.
In particular, as it appears in the last part of §20, it becomes a problem about punishment.

Q: Can a baby be considered a person in Locke’s point of view?
No. Would a lawyer sue a baby because of his mother dying in childbirth? In locke’s account a baby can’t be considered as a person since he has no memories and no experiences.

In Hume’s view, instead, a baby is a person: identity is a relational concept, it doesn’t depend exclusively on personal experience, but also by how others view us.

Thought experiences can be misleading:

  • They may omit some ideas and conditions which might be useful to criticize or accept an experiment
  • Most of the thoughts experiments regard what can be logically conceivable. There is a difference between something being actually possible or logically possible.

Thoughts experiments force our minds to open up and test our theories.

What does Williams want to show:

everybody identify themselves with the psychological theory of identity

According to Hume we continue to call something or someone the same even if they completely changed, because we project our idea of their identity (as personality). Whatever being which doesn’t have consciousness or memory can’t give an idea of the self. This doesn’t mean we can’t ascribe identity to entities which don’t have consciousness because we say that every part is part of a system, where every part has a sense and a place: the term of internal finality is used.

Identity starts to be a problem when the idea of the souls starts to get confused, unclear or questioned. The problem of identity becomes a problem when this happens.

Chuck Palanewk: nothing of me is original, I am a combined form of anyone I’ve ever known.

It’s easier to change when we don’t know anybody

+++ last 10 mins

Hume stated that identity is a fiction: it’s created by our imagination. It works according to the principles of resemblance, contiguity and cause and effect. The former is the most important.

According to Hume memory and imagination are two different sides of the same faculty

Suggested related readings:

  • The mind’s eye, fantasies and reflections on self, edited by Daniel Dennet.
  • Steven Pinker, *he blank slate, biological determinism: we are determined by our DNA
  • Tzvetan Totorov, The Conquest of America. The question of the other
  • concerning Locke’s interpretation of “man” and “person”:
    • Calvino, Il Visconte Dimezzato
    • Stevenson, The Strange Case of Dr. Jekyll and Mr. Hyde (Stevenson probably read Locke)

Next topic: God and Theodicy



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