When Ceri Braum accepted the gift of eternal life, this was not quite what she had in mind. Sure, she knew that her brain would be removed from her body and kept alive in a vat. She also knew her only connection with the outside world would be via a camera, a microphone, and a speaker. But at the time, living forever like this seemed like a pretty good deal, especially compared to living for not much longer in her second, deteriorating body.
In retrospect, however, perhaps she had been convinced too easily that she was just her brain. When her first body had given out, surgeons had taken out her brain and put it into the body of someone whose own brain had failed. Waking up in the new body, she had no doubt that she was still the same person, Ceri Braum. And since it was only her brain that remained from her old self, it also seemed safe to conclude that she was, therefore, essentially her brain.
But life just as a brain strikes Ceri as extremely impoverished. How she longs for the fleshiness of a more complete existence. Nevertheless, since it is her, Ceri, now having these thoughts and doubts, is she nonetheless right to conclude that she is, in essence, nothing more or less than her brain?
Source: Chapter 3 of The View From Nowhere by Thomas Nagel (1986)
Baggini, J., The Pig That Wants to Be Eaten, 2005, p. 112.
While I think it's clear from Ceri's present angst that she was once "something more than her brain," and our deep satisfaction from any number of sensory pleasures makes this obvious as well, the question this thought experiment is really getting at is that of personal identity, which I've already covered quite well.
First off, as I said in my Response to Thought Experiment 2: Beam Me Up: "When considering any of these issues, it's important philosophically to start by pointing out that the question of a soul or some other immaterial part of a person is entirely discounted. I firmly believe this is the correct view of the self though as there is no evidence to the contrary, so I'm happy to skip over that concern."
Next, it has come up in a few other thought experiments, but I first mentioned in my essay on John Locke how personality and identity lies at the crossroads of the Mind x Body intersection. However, as an evolutionary philosopher, I only see evidence for physicalist explanations for the mind, which places it squarely in the brains of our bodies. Our memories and sense of self remain unchanged when we lose a limb, donate a kidney, replace our hearts, or lose our vision, while strokes, brain tumors, or other head trauma have profound effects on "who we are."
I explored this in depth in my Response to Thought Experiment 30: Memories are Made of This, where I wrote: "This is now the second thought experiment inspired by Derek Parfit, who has been highly influential among contemporary philosophers on the subject of personal identity. Parfit is a reductionist, 'believing that since there is no adequate criterion of personal identity, people do not exist apart from their components.' In a late 1990's documentary on Channel 4 called Brainspotting, Parfit described four traditional theories of what components might constitute the self: the body, the brain, memories, or a soul. (You can see Parfit discuss this in two 10-minute clips here: Part 1, Part 2.) As an evolutionary philosopher looking at the evidence in nature...none of the four traditional components tell the story of identity, [so] what are we left with? The way Parfit explains it in Brainspotting, he sees personal identity rather like David Hume saw the definition of a nation. A nation is generally considered to be a group of people living on a portion of land, but it's not just "those people" nor just "that land". However, it's also not something over and above that either—the nation is not some permanent immaterial entity, it's just an ever-changing definition. To Parfit, the individual self can be regarded the same way. It is the totality of a set of perceptions within a body (which includes a brain); it is not just the body or just the perceptions. Problems arise when we mistakenly try to insist on one permanent definition of a single self. We are beings who change over time and our identities do as well."
This changing of identities was explored thoroughly in my Response to Thought Experiment 11: The Ship Theseus, when I said: "The universe and everything in it are always changing in almost infinitesimally continuous ways. We've developed the branch of mathematics called calculus to help describe these tiny changes, but it would be incredibly difficult to keep track of reality this way by calling everything x, then x1, then x2, then x3, etc. on into infinity. It's much easier for our brains and our languages to just call something X and treat this x as a concrete thing even though it actually has very fuzzy borders at the edges. ... This may sound like a silly example concerning an imaginary object of little importance, but I for one will try to remember it the next time I meet my friend called "Jane" or "Joe" or "Mary" or "Mike". They've changed since the last time I've seen them, and Jane724 might have something more to teach me than Jane723 did. And then I can become Edxxxx....."
So in this present thought experiment, Baggini is playing with this notion of how our identities change over time with changes to our bodies or experiences. There's no question Ceri has changed, and since her body did not go on without her brain, we are left with her brain as the last location of her identity. What is interesting to me about this thought experiment is to consider the way Baggini has peeled away pieces of Ceri one at a time, so we could wonder just how far he could take this before Ceri was "gone."
There is a concept I failed to cover in my essay on David Hume that addresses this well, and that is Hume's idea of the bundle theory. (Bundle theory was discussed, though, in the silly Three Minute Philosophy video on Hume that I shared.) According to bundle theory, "an object consists of its properties and nothing more: thus neither can there be an object without properties nor can one even conceive of such an object; for example, bundle theory claims that thinking of an apple compels one also to think of its color, its shape, the fact that it is a kind of fruit, its cells, its taste, or at least one other of its properties. Thus, the theory asserts that the apple is no more than the collection of its properties." The clarity that bundle theory brings to this thought experiment comes when you imagine taking away all the properties of an object one by one until all of them are gone. Once that is done, according to Hume, nothing of the object is left. And so it is in this case, where our personal identity is a bundle of our purely physical body parts plus our mental parts that reside in our physical brains. Take them away one at a time, and "we" are still there in some capacity, but in a way that is understood to be diminished. In this case, Ceri 2 < Ceri 1. If the properties were taken away in a different order, say she suffered a stroke and her decimated brain was replaced with another working brain, then Ceri's body (Ceri 3) would still have life, but it would only be a very diminished sense of Ceri that was still around. In other words, Ceri 3 < Ceri 2 < Ceri 1. It is not until every property of her life has gone that we say Ceri has disappeared. But once all those bundled properties are removed, there is nothing left - no insubstantial, permanent soul. So, to answer Ceri's question, we are quite a bit more and less than our brains, but unless you want to get into cultural survival (best saved for another time), that does not extend to anything beyond our bodies.