I consider myself a man of reason and skepticism, fully invested in the scientific method. Such an inclination makes it quite difficult to justify even entertaining the kind of questions I am purporting to answer here, not least because my anti-theistic streak might make me somewhat hypocritical to even suggest that I have anything close to an untestable belief system. Regardless, we all ponder the questions no one can answer. Even the most hard-line rationalists such as myself.
What triggered these thoughts most recently was an article discussing the time at which an unborn child becomes a person, in the eyes of Arizona legislation. The suggestion was that according to the law, a child has rights at ovulation, even weeks before it has been conceived, which is laughably preposterous by conventional standards.
But still, it prompted me to consider (as I have done on numerous occasions before) what it is that makes us, the postnatal homo sapien, so apparently special. Yes, we have opposable thumbs, we walk upright, we have unusually large brains capable of complex thought processes, but what is it that makes us feel so entitled, as developed members of a species, to act on either other species or the unborn members of our own with such little regard for their own wellbeing? What makes it OK to abort a foetus or slaughter a delicious cow, but not to stab someone and take their money, or abduct and molest a young child to satisfy your own decadent desires?
When considering unanswerable questions, it does no harm to use a scientific foundation. In fact I would argue its case as a requirement, otherwise it becomes a futile exercise in quasi-intellectual masturbation, of little inherent value outside fantasy fiction (but let's leave religion out of this, for now). Scientific knowledge and logical reasoning is the best system of constraints within which to work, if we are to approach anything resembling a truth.
Biologically speaking, what separates us as humankind from the rest of life as we understand it is not a great wall or crevasse, but merely a fuzzy border embedded in the highly multidimensional, vast continuum of genome-space. The genome is sufficiently expressive to encode even the tiniest variations in life-building processes, most of which would be undetectable to the naked eye. Such variations may have compounding effects due to selection pressures, and at some point a new species may be considered to have emerged—to have diverged—when it is no longer possible for it to successfully interbreed with its cousins.
So we as humans may be considered "different", by the above standards at least, from modern primates such as the chimpanzee. However, inbreeding issues notwithstanding, had selection pressures been sufficient enough to effect divergence, yet relaxed enough to keep all intermediate species alive somewhere on Earth, enough of an overlap would exist such that it would be possible for humans to successfully procreate, albeit in a large number of intermediate steps, back up the "evolutionary tree" to the point of a common ancestor, and back down to the chimpanzee. I'd imagine that the fruits of such labour—namely a continuum of human descendents who, at one extreme, are technically no longer a human, but are indistinguishable from chimpanzees—would be extremely challenging to most legislation!
But need we take such a long-winded path, or is there a more direct possibility? The "miracle of birth" is no longer much of a miracle. We now understand the biological processes that occur during conception well enough to avoid invoking the supernatural—for all except one thing: the creation of a consciousness.
Do we have any reason to believe the creation of a consciousness is limited to times when a loving couple copulate naturally? If so, we have to consider those born of e.g. rape or otherwise unloving sexual acts such as in vitro fertilisation (IVF, "test tube babies") to be somehow less human. But if not, we have to abandon the requirement of some magical process involving love, and conclude by accepting that artificial creation of life is equivalent to the natural phenomenon. Even if one were to (absurdly) attempt to argue the case for non-equivalence, what would they make of a child of a pairing of a natural born human and a rape child? Is the "consciousness allele" (to abuse the term allele) recessive or dominant in such circumstances? And is it manifest in any observable way such that it could be subjected to selection pressures either encouraging or discouraging its propagation? These questions are moral minefields, but for the sake of rigour I must acknowledge their existence.
So let's suppose that artificial creation of humans is sufficient to create a consciousness. In such a case, what if we perturb the genome in some way? What if we combine it in a fashion similar to that which occurs during sex? What if we mutate it so much that it is no longer possible to reasonably call it a "human" genome? And supposing it survives beyond a few agonising minutes, what do we make of the life we have created? Is it a conscious being?
Due to the approximately continuous, infinitesimal nature of such genetic perturbations, if one was to argue the case for a lack of consciousness in arbitrarily created life, they would have to propose a threshold of human-likeness (or otherwise) under which consciousness was no longer possible. I believe this possibility to be highly unlikely—if the only way we could fall short of such a threshold is by mutating the genome, then consciousness would have to be part of a poorly understood part of the genome, or otherwise encoded within it in some undetectable way. The poorly understood parts are shrinking as we discover more about the genome, and I may simply assert that the Universe is not conspiring against us to invoke steganography or similar deception techniques on the human genome. Therefore my conclusion is that artificial life created from an arbitrary genome does qualify as conscious.
If we are satisfied that both naturally born humans and artifically born, arbitrary lifeforms are conscious, then I make a small jump to generalise and assert that all life is conscious, to some extent.
What makes ants an interesting vehicle for this argument is their tendency to swarm. While each individual ant in a colony is not capable of much, the colony as a whole is a highly intelligent entity, capable of devouring beasts and plant life orders of magnitude greater in size. (The BBC ran a two part nature series entitled Swarm documenting the incredible behaviours of a range of wild, swarming species. I strongly encourage people to watch it, if only for the breathtaking high-definition footage!)
It is fascinating to contemplate the power of combining such beautifully simple components into larger machines. We have ants comprising very little individual intelligence, in some cases completely blind and relying on pheromone trails alone (occasionally to their ultimate demise), banding together by the thousands or millions to not only survive but prosper. We have the humble 20 nanometre transistor, capable of switching a current on and off, etched a billion at a time onto a silicon wafer to produce a microprocessor that will compute billions of calculations each second. We have the human neuron, a simple nerve cell, connected to billions of others via synapses in the nervous system, allowing its host to contemplate and type out this essay.
All of these systems share the trait of being simple, massively connected entities. It's the co-operation of a large number of simple pieces that creates an otherwise impossible machine. I argue that it is this co-operative nature of a network of connected, highly interacting matter that quantifies consciousness in a being.
At this point, you may be gagging at the suggestion of a microprocessor—a machine—possessing a consciousness. Let's look at some more scientific facts.
The nodes in neural networks, namely the synapses, communicate through electrical and chemical signals for which we have proven physical theories. It is these same theories that allow us to create electrical components such as transistors, and by extension microprocessors. Fundamental physics—the most basic mechanisms of the universe we currently aim to understand—is all about interactions of the different physical "fields": the electromagnetic force, the strong and weak nuclear force, the gravitational force, etc. When you downcast the issue of co-operating networks to this level, there isn't a whole lot separating the interactions of neurons in the brain from the interactions of ants in a colony, or from those of transistors in a working microprocessor. What clearly does differ, however, is the nature of information stored in each of these three examples, which is what ultimately determines the behaviour of the being.
All of these networks exhibit programmed behaviour in response to external stimuli. A human is programmed to tend to a crying baby, an ant colony to seek out food, a microprocessor to calculate curiously eyebrowed avian trajectories. These behaviours are not inherent to the design of the networks, but are the result of evolution in the natural case, and intentional human design in the computer case. Other programmed behaviours in the human brain include the capacity to love, to feel anger, compassion and empathy, to respond to pain and to another's display of pain, etc. Many would like to think that these behaviours are aspects of the consciousness, but in truth we know that this can simply not be the case—to reiterate, they are evolved behaviours that would still exist even in the absence of consciousness.
So, we have reduced the definition of a consciousness down to something more fundamental, but far from trivial. It is the I in me and the you in you. Perhaps we are connected as one, but without the neural connectivity to realise it, we could never "know" that feeling on any human level—we don't just wake up with each others' memories. I like to think of my own consciousness as being the Universe's ability to experience itself through the lens of my mind.
In conclusion, I propose that all matter is capable of consciousness: the brain in your head, the ants in your garden, the unborn foetus in an expectant mother, the chair you are sitting on, the earth beneath your home and the stars in the sky. The degree of consciousness is a function of network expressiveness and bandwidth, and the boundaries of a network are perhaps not as simple as we may think.