Introduction and Context:
In describing what philosophy does, I’ve heard Prof. Todd Jones (of UNLV) say “philosophy is usually about one of two things: Things that are so abstract and obscure that most people wouldn’t bother to think about them, and things that are so obvious that most people wouldn’t bother to think about them.” Substance dualism falls into the latter category. For most people, that humans have an immaterial mind/soul that is independent from their body is so obvious, it’s not even something to question…but this is a philosophy class!
Up until now we’ve looked at what substance dualism is, how Descartes argued for it, and one of it’s main problems–the interaction problem. Now we’re going to look at another argument against substance dualism: the communication problem (aka argument from brain damage). The communication problem is that substance dualism gives a very poor account of why brain damage (i.e., damage to a physical system) has an effect on the mind (i.e., an independent non-physical system). That is, if the brain and the mind are two distinct entities, and the immaterial mind can exist intact and fully functional for eternity without a body (i.e., brain), why should brain damage matter to mental abilities now–when we have a brain?
Essentially, the argument is that the physicalist model give a comparatively better account: it says certain parts of the brain are responsible for certain functions. If you damage those parts, you’ll diminish or lose those functions.
Brain Damage: The Case of Clive Wearing
The communication problem becomes apparent when we consider how substance dualism would account for loss of mental capacities caused by brain damage.
Consider the famous case of Clive Wearing (CW) who, after having a normal life for 50 years, contracted viral encephalitis. The end result of the encephalitis was anterograde and fairly severe retrograde amnesia. The former is when you can no longer form new memories, the latter is when one cannot recall events from before the brain damage occurred. Brain scans on CW showed that the areas associated with memory had, for the most part, been destroyed by the virus.
It’s a Communication Problem: The Dualist Account of Brain Damage
The dualist account of brain damage cannot imply that damage to the brain would cause damage to the mind. Since the mind isn’t the brain and the mind can persist eternally regardless of whether we have a physical brain or not, they have to explain why brain damage apparently causes loss or diminishment of mental functions. I emphasize “apparent” because the dualist cannot answer that damage to the mind can actually occur as a consequence of damage to the brain. Otherwise, how do you explain how the soul function and exist eternally once the brain is worm food? For this reason, the dualist instead has to argue that the mental damage is only apparent.
The dualist has to argue that the mind remains perfectly intact but something’s gone wrong with the mind-brain interface. We can think of it like this: the brain has within it a “modem” or “router” that transmits stuff about the body to the mind and also receives information from the mind (to be converted into physical movements). In the case of brain damage, what has gone wrong is not that the mind doesn’t function perfectly (it still does), it’s that the modem/router isn’t working for certain types of operations. In short, for the dualist, brain damage is a communication problem between a damaged physical system and an undamaged non-physical system.
Two Possible Dualist Replies
There are two possible dualist accounts of why the communication between mind and body fail. The first is that the perfectly intact mind sends information to the brain, but upon receiving the information, the brain messes it up somehow. The second is that the brain, because it’s broken, sends the mind distorted information and so that’s why new memories can’t be formed. Lets flesh these out…
Option 1: Distorted Input
Think back to CW with his anterograde and retrograde amnesia: When he is asked if he remembers his wedding, he replies he doesn’t. The dualist has to say that this memory is perfectly preserved in his undamaged immaterial mind. When someone asks him, “How was your wedding?” in his immaterial mind he perceives it perfectly but the receiver in the brain somehow mistranslates his intended answer (the description of the memory) to “I don’t remember.” The receiver in the brain takes the mind’s input of clear coherent memories and garbles it, thereby causing the output “I don’t remember.”
On this account, poor CW has total access to the memories. They are as vivid and clear to him as they were pre-brain damage. He just can’t express them to people.
This, on it’s own, seems quite implausible but it gets worse. CW’s retrograde amnesia doesn’t apply to all his memories, it’s not complete. If you ask him if he is married, he will say “yes.” Why is it that for some memories the “modem” garbles the input from the mind and in other cases it doesn’t? Does each memory have a separate modem? That doesn’t seem very plausible…
The other difficulty is to explain why, when the modem garbles the mind’s input, is the output always “I don’t know”? Why not “gjkdajfopjoqwjfoa[jfo[asj[fj’ljkd!” or “I like ice cream”? And why does it garble in these ways for memories about the wedding but not for memories about whether he’s married?
Although the physicalist model is still a work in progress, its account (brain equals the mind, damage to brain equals damage to mind) seems much more plausible and in line with our best current scientific knowledge.
Option 2: Distorted Output
The other possible response the dualist can give to explain why damage to the brain is only apparent (but not real) damage to the immaterial mind is to say the communication problem is from the brain to the mind.
In the case of anterograde amnesia, the brain is trying to send new memories to the mind for storage, but the modem is down, and so they never arrive. Kind of like if you tried to upload something to the cloud but your modem is down. The information can’t get to where it needs to go to get stored and so it is never encoded. So far this sounds plausible…except 2 things.
The first problem is that it seems to presume new memory formation requires having a physical brain. The dualist, in essence is saying, he can’t form new memories because the part of the brain that sends experiences to the mind isn’t working. The implicit assumption here is that memory formation requires having a brain! This is something the dualist cannot abide. On the other hand, if your mind can form new memories without a material brain, then why is the brain damage a problem in the first place?
If the immaterial mind can’t acquire new memories except through the intermediary of the physical brain, how’s this going to play out in the “ever after.” Will you never be able to form any new memories once your body has decayed? Are you stuck for all eternity with only the memories you acquired in your brief stint on earth? Eternity is a long time. That might suck for more than a few people. It’s certainly motivation to do some crazy shit in your life. Maybe Drake should have said “YOFMO”: You Only Form Memories Once…
The second problem is this: Suppose we ask CW, “do you remember your wedding?” The sound waves enter his auditory system and get converted into a neural signal which gets sent to the brain. But since the modem that sends signals from his brain to his immaterial mind isn’t working right, the message “do you remember your wedding” comes out as gibberish. The mind never receives the right question even though it contains the information to answer the question.
Up to this point, it’s still a moderately plausible account. However, if the mind is receiving gibberish, why does CW respond “I don’t remember” rather than “I don’t understand a damn word you’re saying!”
Understanding the question doesn’t seem to be the real problem. That signal is getting through just fine: he just doesn’t know the answer to it because he doesn’t have that information.
Additional Arguments Against Dualism
Argument from Phylogenesis
At what point in the evolutionary process the organisms get “souls”? Most people (except maybe Leibniz) would say that one celled organisms don’t have souls. So how about 2 celled organisms? No? What about 3? …4? 100?
Recall that for the dualist you can’t have partial souls, so the dualist can’t say that mental capacities gradually evolved along with complexity. Either you have a complete functioning soul or you don’t. This means that at a certain point in evolutionary development a parent didn’t have a soul while the offspring did. The metaphysical commitment to the existence of metaphysically independent immaterial souls makes the existence of souls difficult to square with our best scientific knowledge of the development of life.
Argument from Ontogenesis
The argument from ontogenesis is similar to the previous argument but applies at the level of the individual organism. Consider how an individual human develops. Most people, including dualists, will say that neither the sperm or the egg has a soul. When the two touch to form a single cell, does a soul appear too? If so from where? How do we know? Does a single cell have a soul? If not, then how about when that cell divides and becomes 2 cells. Now does it have a soul? What about after there are 4 cells?
The idea that “poof” a soul appears after a certain number of cell divisions is going to be difficult to defend. It’s just as problematic as defending the idea that a soul appears for a single cell the moment the sperm penetrates the egg.
To a certain extent, defending against the arguments from phylogenesis and ontogenesis require to dualist to make empirically defensible claims about when the soul appears. This will be tough.
Introduction and Context: