Extended Mind Thesis

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Where are the boundaries of the human brain?

Taken literally, you might answer that the brain ends where the brain matter ends. White matter at the core and grey matter layered atop it, cerebrum, divided into two hemispheres, a cortex divided into the neocortex and allocortex, both of which themselves divide into several layers, which can be further divided into ventricles, fluids, glands, ganglia, and each of these yet further divisible into neurons that are wired into a complex circuitry that channels neurotransmitters from place to place in response to nerve impulses: a tweak in electric potential in a cell which changes rapidly, triggering the transmission of signals from axons to synapses, motor cells, and glands.

We might also define the brain as the combination of frontal, parietal, and occipital lobes.

We could say that it’s the dominant lump of matter contained within the skull, suspended in cerebrospinal fluid, almost completely walled-off from the bloodstream, and thus, many of the body’s transmission channels, by a blood-brain barrier.

We could also, thinking more broadly, expand our definition to encompass the whole of the central nervous system, including the spinal cord, or the larger, more complete nervous system, which would bring detection infrastructure like nerves into the mix, going with the assumption that while the brain and spinal cord do the bulk of a person’s processing, there are also on-site calculations happening within a person’s body-spanning nervous tissue which plug into the mixed bundle of nerves contained within the spine, which in turn connects back to the brain.

We could go still further and include sensory neurons, which are located in the skin, as is the case with cutaneous receptors, and within our muscles, as with the muscle spindles that detect and transmit information about stretch in our muscle fibers back to the larger nervous system network.

Expanding our definition in this way, the whole of the human body very quickly comes to seem like part of the brain: part of what allows us to collect information, to process the information that we collect, and to act upon that information once we’ve had the chance to parse it.

This concept gets even more complex, though, when you consider that some of the information we receive from within our bodies doesn’t actually come from human cells, but rather from non-human portions of our microbiome, which communicate data about what’s happening in our gut, for instance, which we are then able to utilize the same way as if it had come from one of our distinctly human components.

If information coming from these types of non-human objects contained within our bodies can be considered internal, considered to be the work of our larger brain structure, why shouldn’t other non-human components be thought of in the same way?

This is the logic behind the Extended Mind Thesis, which posits, in essence, that our minds are the sum of not just our biological components—human and non-human microbiome pieces—but also the external objects we use to aid us in our collection of information, computation, and memory storage.

Which is a fairly boggling claim, but also quite an interesting way to view many of the tools we’ve invented as a species throughout history, and the ones we continue to use, today.

Through this lens, the abacus was an impressive bit of brain-augmentation, allowing us to calculate far more swiftly than we were capable of doing before, and computers with modern processors and whiz-bang upgrades even more so.

The internet and other long-distance communication devices become something akin to telepathy, but they’re also a bit like world-spanning sensory organs that allow us to collect information about our environment—our conception of which is growing larger and larger—and then process and act upon that information.

This means that offloading our knowledge about birthdays to Facebook, and relegating phone number memorization to our smartphones, are both acts of tool-augmented distributed memory.

We latently perceive these tools, according to this concept, as extensions of ourselves, rather than as completely separate objects, and thus we come to rely on them differently than we would other sorts of technology. And although most of us probably wouldn’t say we consider our smartphones to be extensions of our brains, if asked, we do tend to behave as if they are, in certain circumstances.

Because of this instinctive incorporation of such tools into how we think, how we process, how we store information, we could learn to utilize these tools even more intuitively, lessening the amount of transmission time that would otherwise exist between us and these neural add-ons.

That said, there are fair and worthy arguments against this thesis.

Among them, that by extending the definition for brain in this way, an extension achieved by allowing the concept to become increasingly metaphorical rather than literal, we may as well consider the whole of existence to be part of our brains. Our inputs and processing are so reliant on our environments to function optimally that we can’t say for certain, using this logic, that any random thing in our environment—the pebble in the road, the dried gum stuck under the seat in front of us on the bus, the particulates in the air we breathe—didn’t trigger a connection deep within our neurons; which by some, expansive definitions could make those pebbles and bits of chewed gum and particulates components of our human computational system.

It’s also possible, and perhaps desirable, to draw the line between the processing and information storage components of our brain, and the components that engage with, collect data from, and interface with the rest of our bodies, and the rest of the world. According to this way of thinking, the fact that there are neurons in our skin is irrelevant, just as it’s irrelevant that our brain tissue is made up of the same fundamental materials, if you zoom in far enough, as our livers, as a toad’s eyeball, and as a blade of grass or speck of dust.

That things are similar in composition at some scale is not an indication of connectivity, in other words: it’s just an indication that there are finite likely arrangements of matter. Such materials being used for superficially similar things in different portions of the body doesn’t mean they are the same thing.

Not all things made of carbon are the same, and not all neurons are the same, even if they share some of the same structure and utility.

Thus, endlessly increasing the scope of how we define a brain could render the whole concept meaningless.

Those criticisms noted, though, the extended mind thesis provides us with a compelling way of looking at the world, and could help explain the attachment we feel to certain types of technologies: especially those for which we form something like a reliance, because we’ve offloaded so much of our internal storage, memory, and processing onto them.

It’s possible to see such technologies and other external components as add-ons in some circumstances and as completely separate entities in others, however, and in order to avoid being too reductive in either direction, and in order to avoid instilling too much meaning in a thesis that may very well be biased toward computer-centric metaphors, it’s probably best to straddle the fence on this one, in most cases.

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