For a long time people thought that the self was unified and eternal. It’s easy to see why. We feel like we have an essence; we grow old, gain and lose friends, and change preferences but we are the same person from day one.

The idea of the unified self has had a rough few centuries however. During the English Enlightenment Hume and Locke challenged the platonic idea of human nature being derived from an essence; in the 19th century Freud declared that the ego “was not even the master of his own house;” and after decades of revealing empirical research neuroscience has yet to reveal anything that scientists would call unified. As clinical neuropsychologist Paul Broks says, “We have this deep intuition that there is a core… But neuroscience shows that there is no center in that brain where things do all come together.”

One of the most dramatic demonstrations of the illusion of the unified self comes from Michael Gazzaniga, who showed that each hemisphere of the brain exercises free will independently when surgeons cut the corpus callosum. Gazzaniga discovered this with a simple experiment. When he flashed the word “WALK” in the right hemisphere of split-brain patients they walked out of the room. But when he asked them why they walked out all responded with a trivial remark such as, “To go to the bathroom” or “To get a Coke.” Here’s where things got weird. When he flashed a chicken in patients’ left hemisphere (in the right visual field) and a wintry scene in their right hemisphere (in the left visual field), and asked them to select a picture that goes with what they saw, he found that their left hand correctly pointed to a snow shovel and their right hand correctly pointed to a chicken. However, when the patients were asked to explain why they pointed at the pictures they responded with something like, “That’s easy. The shovel is for cleaning up the chicken.”

Nietszche was right: “We are necessarily strangers to ourselves…we are not ‘men of knowledge’ with respect to ourselves.”

But you don’t have to have a severed corpus callosum or a deep understanding of Genealogy of Morals (which I don’t) to appreciate how modular ourselves are. Our everyday inner-monologues are telling enough. We weigh the pros and cons between fatty meats and nutritious vegetables even though we know which is healthier. When we have the chance to procrastinate we usually take it and rationalize it as a good decision. We cheat, lie, are lazy and eat Big Macs knowing full well how harmful doing these things are. When it comes to what we think about, what we like and what we do Walt Whitman captured our natural hypocrisies and inconsistencies with this famous and keenly insightful remark: “Do I contradict myself? Very well then I contradict myself, (I am large, I contain multitudes.)”

That the unified self is largely an illusion is not necessarily a bad thing. The philosopher and cognitive scientist Dan Dennett suggests that it is a convenient fiction. I think he’s right. With it we are able to maintain stories and narratives that help us make sense of the world and our place in it. This is a popular conviction nowadays. As prominent evolutionary psychologist Steven Pinker explains in one of his bestsellers, “each of us feels that there is a single “I” in control. But that is an illusion that the brain works hard to produce.” In fact, without the illusion of selfhood we all might suffer the same fate as Phineas Gage who was, as anyone who has taken an introductory to psychology course might remember, “no longer Gage” after a tragic railroad accident turned his ventromedial prefrontal cortex into a jumbled stew of disconnected neurons.

However, according to the British philosopher Julian Baggini in a recent TED lecture the illusion of the self might not be an illusion. The question Baggini asks is if a person should think of himself as a thing that has a bunch of different experiences or as a collection of experiences. This is an important distinction. Baggini explains that, “the fact that we are a very complex collection of things does not mean we are not real.” He invites the audience to consider the metaphor of a waterfall. In many ways a waterfall is like the illusion of the self: is it not permanent, it is always changing and it is different at every single instance. But this doesn’t mean that a waterfall is an illusion or that it is not real. What it means is that we have to understand it as a history, as having certain things that are the same and as a process.

Baggini is trying to save the self from neuroscience, which is admirable considering that neuroscience continues to show how convoluted our brains are. I am not sure if he is successful – argument by metaphor can only go so far, empirical data wins at the end of the day – but I like the idea that personal and neurological change and inconsistency doesn’t imply an illusion of identity. In this age of cognitive science it’s easy to subscribe to Whitman’s doctrine – that we are constituted by multitudes; it takes a brave intellect, on the other hand, to hang on to what Freud called our “naïve self-love.”

Shakespeare opened Hamlet with the huge and beautifully complex query, “Who’s There.” Four hundred years later Baggini has an answer, but many of us are still scratching our heads.

Volpe BT, Ledoux JE, & Gazzaniga MS (1979). Information processing of visual stimuli in an “extinguished” field. Nature, 282 (5740), 722-4 PMID: 514351