And assuming we can answer that, how is science changing it?

Big philosophical concepts bother me, but I am expected later this week at Tufts University, where I’ll be on a panel discussing “The New Biology and the Self.” So I need to get over my reluctance to talk about the self. And it’s not the only big idea that gives me trouble.

Consciousness and free will are two other notions that seem to evaporate as you approach them. You can do brain imaging studies and find out what parts of the brain are active when these states emerge, But what does that tell you, really? Some circuit or other is humming while we are self-aware or while a “free” choice is made. So? This tells us what these human experiences look like to an observer at the physiological level. It doesn’t say anything about the subjective experiences that we are really curious about.

Something similar applies to the “self.” We can describe it from the outside, but it is our subjective experience of it that matters. The  cognitive psychologist Ulric Neisser used to talk about different parts or varieties of the self—the cognitive self, based on tendencies to perceive and think in certain ways; the ecological self, owing to a person’s particular situation in the surrounding environment; the narrative self, arising from a more or less coherent story we tell ourselves about our lives. But after holding a series of conferences on five different kinds of “self,” he seemed to end in disappointment, thinking that it’s not a terribly useful word.

The self sounds to me in part a lot like consciousness. Not the consciousness of which a playful dog has more than a sleeping philosopher, the state you measure on a scale of stupor and coma; rather the awareness of our inner lives, an ongoing binding or bundling of sensations, actions, feelings, and thoughts, the awareness of our awareness. Metacognition, some psychologists call it.

No one knows how this works. Clearly, Descartes’ claim notwithstanding, there is no “homunculus” or little person inside the mind watching everything else (which only leads to an infinite Russian-doll regression of one homunculus inside the next). Somehow the mind watches itself; somehow the brain gets and gives us a subjective sense of both consciousness and self.

As for free will, there are determinants of every human choice, and determinants of those determinants, and so on back through development to the genome and then back beyond that through evolution. However, because no one, including ourselves, can ever trace that chain of causation—it is formally chaotic and thus empirically unknowable due to sensitivity to initial conditions—we have no alternative but to rely on our subjective sense that we are making a free choice, and hold ourselves and each other responsible accordingly.

But assuming each of us has a self—or several—what does “The New Biology” imply for it or them? I can easily think of three things.

First, the revolution in genomics, especially personal genomics, is gradually giving us all the chance to find out what ethnic groups our ancestors came from and what diseases and even behavior patterns we are predisposed to. Some of this information may be useful, some interesting, some scary. Suppose you are prone to a disease—Alzheimer’s, or some cancers—that nothing can be done about. Suppose you have genes that predict criminality, or falling in love with the wrong person. Of course, you can refuse to have your genome done, but you haven’t really escaped, since you are now in your own eyes and  those of others the person who chose not to know, which is not the same person you were before you had the choice.

Second, the brain imaging revolution can theoretically find the neural activity associated with every act, thought or feeling. Does that make your brain you? Do you want to know what is going on in there when, for instance, you look at a picture of your wife, boyfriend, or son? Whether your charitable donation was done out of the goodness of your heart, to snatch some pittance out of the jaws of the IRS, or just to show off? Again, the objectivity of the method appears to change our sense of ourselves, even if we reject the chance to know.

Third, the constant stream of new enhancement drugs—let’s just consider the prescription ones—that  can change thoughts, feelings, even actions. Stimulants for alertness and cognitive function, modafinil for a controlled sleep-wake cycle, Prozac and the like for sadness, Viagra and Cialis for sexual readiness. Memory enhancers seem to be right around the corner. Every one of these is an intervention we can now (with a little help from our friendly doctor) more or less make upon ourselves.

Is the chronically sad self now a happy one, or just a sad one with a drug on board? Is the long-desexualized elderly man really sexual again, or is the viagrafication just below the belt? Is the student who couldn’t concentrate without Adderall really different? One thing is for sure: we all have a lot of new questions to answer.