Sunday, 20 April 2014

The Sum of our Parts

"And that's what I've done. Maintained it for 20 years. This old brooms had 17 new heads and 14 new handles in its time."
"How the hell can it be the same bloody broom then?"
"Theres the picture. What more proof do you need?"

Triggers Broom Paradox raises some interesting questions in the light of the extended mind and embodiment topics that we have looked at in the last few weeks. OK I'm being a little facetious here, I should give this scenario its more respectful moniker - Theseus Paradox. However the question remains as relevant. If we replace the constituent parts of an object piece by piece (and unlike Trigger we only need to consider a single instance of replacement), would it still be the same object. And if that object theoretically was a human or other biological creature would we still believe this to be the case?

This is a very challenging theoretical condition for us even to consider. It is very easy for us to relate to organ transplants and most people will be one degree removed from someone who has one, and we seem comfortable thinking of organs simply as functional entities - pumping stations, cleansing devices, manufacturing centres and so on. Similarly we are entirely at ease with the thought of replacing many of our internal and external facilities with artificial devices - bones, muscle and limbs. Some aspects of organ or limb replacements make us a little more uncomfortable, particularly those that involve transplant from one person to another such as face transplants or hand transplants, however it is a significant mental leap for us to consider what it would involve replacing every part of ourselves piece by piece.

In such an exercise, determining if we had a "new us" is still a difficult question. There are epiphenomenal considerations to defining the essence of us, and the answer to whether or not it can be replaced piece by piece many be *easier* if we were to take a reductive physicalist position in which we could posit the view that if we were to replace all the neurons in our brain we might have a new instance of ourselves, although we still might ask the question of which neuron it was that broke the camel's back. Taking an embodied or even extended mind position makes it a much more difficult equation

It is a question, due to its scope and nature that may never come close to finding answers in neuroscience. Many cases brain damage have been reported on which have resulted in dramatic temporary and permanent changes in behaviour &  personality leading others to report that they are "not the same person anymore" however the outward presentation of behaviour and personality alone is surely too shallow a view on our essence. So if not Neuroscience then where? Like many things in life, further clarity can be found in the works of Johnny Cash.

In his book "Johnny Cash and Philosophy", John Huss gives the Ship of Theseus a more contemporary telling (along with many other Cash-related identity questions). Cash had raised similar issues in his song "One Piece at a Time" in which his subject works in an automobile factory and sneaks a part out every day for several years to builds himself a car out of the parts. Unsurprisingly the result turns out more Frankenstein's Monster than Cadillac Seville. Huss presents us a puzzle which challenges our what our preconceptions might be on the essence of any object.

Huss asks what if we replaced Cash's green 54 Plymouth while he slept with an identical car. We agree that the next morning Cash won't be getting into the same car. OK so what it we take his car, completely dis-assemble it overnight and then put it back together. Is it still the same car he drove yesterday? It definitely had a gap in its existance right? So what if now we take the identical car we had in the first scenario, break it down into all its parts, and then piece by piece replace all the parts in Cash's car with the parts from the identical car? What if instead of doing this in one go overnight it is done over months so that the car Cash drives every day is slightly different from the day before. And what, prior to replacing that very last part (say a hubcab) can we say about the car? Is it still the same one Cash was driving? It would seem stange that the addition of a final part should change that. And to complicate things further, What if, when replacing the parts, we took away all the parts being replaced and separately rebuilt these into a car?

It's a puzzle which is obviously made vastly more complicated when we consider it in the context of humans. If we could take a basic mind = brain view it would be be complex by manageable but in the context of embodiment, extended mind, social congition, etc, it doesn't really seem imaginable that we could solve it.

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