A zombike is a regular bike that lacks the quality of impetus, so when you push on the pedals, nothing happens! (Actually this is a restored 1887 Rover Safety Bicycle, details at vintagebicycle.wordpress.com. Thanks to Tim Dawson for photo.)


In 1675, French chemist Nicolas Lemery foreshadowed the guessing game “20 Questions” when he classified all material things into animal, vegetable or mineral. A century later his countryman, pioneer chemist Antoine Lavoisier, narrowed the field down to two kinds of basic stuff: organic (animal and vegetable) and non-organic (everything else). Later (1815) Swedish chemist Johan Berzelius proposed that organic compounds were produced in the presence of a vital force (élan vital), without which living matter was impossible. So rigid was the distinction between organic and non-organic compounds that it was generally agreed that organic compounds couldn’t be created artificially.

Until 1828, that is, when Germany’s Frederich Wohler synthesized urea (an organic compound) from inorganic ammonium cyanate. Which pretty much put paid to vitalism, the view that life involves a special something that cannot be explained solely in terms of chemistry. (Aristotle, the original founder of vitalism, believed that it was the soul that kept the organism alive. Death is when the élan vital, or soul, leaves the body.)

Nowadays, we understand that life happens — it can’t help it! — as a result of complex and interrelated biological functions, which stop working when something dies. Science did away with the need for a spirit/soul/élan vital, the ‘something extra’ that made a physical organism alive. (This isn’t to say for sure there isn’t an extra ingredient- just that it’s unnecessary to explain life.)


Maybe consciousness will turn out to be like this: a superfluous “something extra” to life. There’s this thought experiment involving zombies. Not undead B-movie zombies from Haiti, but rather “philosophers’ zombies.” These are folks just like you and me, completely indistinguishable from us, but they have no sensation of consciousness, no “inner life.” Sure, they talk about their feelings, sensations, loves, memories and all that (since they’re indistinguishable from us). The idea with this thought experiment is that no one can tell a zombie from the likes of you or me; but inside them, it’s blank. For now, please pretend they are possible.

It would then seem that “you” — good old regular, reading-this-column you — has something extra that a “zombie-you” wouldn’t have. Call it consciousness.

So the question is: might this property consciousness turn out to be like the old élan vital? That in a few years, or a few hundreds of years, we’ll convince ourselves that is simply inevitable when you have a complex organism with a trillion-neuron brain, like us.

That is, if you have a complex human body and brain, you’re conscious. There’s nothing more to explain. In this view, a philosopher’s zombie is an impossibility. A human built like you or me is conscious, by definition. If it walks like a duck and quacks like a duck…


Someone — I forget who — spoofed dualism by inviting us to imagine a “zombike,” a regular bike in every way except it lacks the ingredient of impetus, so when you push on the pedals, nothing happens! This is one ‘solution’ (make it go away!) to what’s been called the Hard Problem of Consciousness, which can be easily stated: How can physical processes in the brain give rise to subjective experience? … or, How can brain-stuff be mind-stuff? You can add a verb in there—” … generate mind stuff” or “… be correlated with mind stuff” — but then you start getting squirly, implying that brains and minds are two different things and consist of two different kinds of stuff: physical brain stuff, the hardware; and non-material mind stuff that gives rise to thoughts, i.e. consciousness.

This point of view (which almost no scientists hold nowadays) is known as “substance dualism,” articulated some 500 years ago by René Descartes. Substance dualism is what English philosopher Gilbert Ryle derided as the “ghost in the machine” idea. He raised many objections to it, the clearest of which is what appears to be the insurmountable problem of interaction: How can something non-material (thoughts) affect-or be affected by-something material (brain).

It’s been called the “Casper problem”: How can Casper the Ghost both float through walls (no interaction) and pick up the shirt that fell off the clothesline (interaction)? “Thoughts affecting brains” (and vice versa) implies that either thoughts are some kind of matter or energy (in which case they are material) or else you have to fall back on that old stand-by: Magic!

So for now I’ll stick with the word “mind” being more like a verb, a metaphor for happenings in my brain, an “emergent property.” Or as artificial intelligence pioneer Marvin Minsky put it: Minds are simply what brains do.