(And yet, as a brief aside, that's more than what Artificial Intelligence researchers, or those who think we can "upload our consciousness" to computers, seem to think is sufficient for their pursuits. As Hume said, reason is the slave of the passions, but without the biochemical ability to stimulate pleasure and pain, how can silicone circuits ever feel passions to drive their logic? They can't. But more on that another time.)
So pain—the focus of this week's thought experiment—has been an important subject for philosophers since the beginning of the field. Not only are we concerned with the morality of actions that cause suffering for individuals across society, but examining pain can trigger deeper questions about the nature of reality behind such consequences too. As the Stanford Encyclopedia of Philosophy explains, pain is:
"...the most prominent member of a class of sensations known as bodily sensations, which includes itches, tickles, tingles, orgasms, and so on. Bodily sensations are typically attributed to bodily locations and appear to have features such as volume, intensity, duration, and so on, that are ordinarily attributed to physical objects or quantities. Yet these sensations are often thought to be logically private, subjective, self-intimating, and the source of incorrigible knowledge for those who have them. Hence there appear to be reasons both for thinking that pains (along with other similar bodily sensations) are physical objects...and for thinking that they are not. This paradox is one of the main reasons why philosophers are especially interested in pain."
Once again, the mind-body problem comes alive. We have had trouble finding a fully physical, bodily definition for pain, so some philosophers turn for an explanation to an imaginary realm of ideas or minds, which must operate in a separate plane of existence. But even if you don't agree to such dualism, then which of the many flavours of monism make the most sense? Let's read the thought experiment now and then dive into these issues.
The accident left David with a very unusual form of brain damage. If you scratched, pricked, or kicked him, he felt no pain. But if he saw a lot of yellow, tasted oak, heard an opera singer hit a high C, made an unintentional pun, or had one of several other apparently random experiences, then he would feel pain, sometimes quite acutely.
Not only that, but he did not find the sensation of this pain at all unpleasant. He didn't deliberately seek out pain, but he did not make any efforts to avoid it either. This meant that he did not manifest his pain in the usual ways, such as crying out or writhing. The only physical signs of David being in pain were all forms of involuntary spasm: his shoulders would shrug, eyebrows lower and rise in quick succession, or his elbows flap out, making him look like a chicken.
David's neurologist, however, was deeply sceptical. He could see that David no longer felt pain as he had before, but whatever David was now feeling when he saw "too much yellow," it couldn't be pain. Pain was by definition an unpleasant thing that people tried to avoid. Perhaps his brain damage had made him forget what the sensation of real pain felt like.
Source: "Mad Pain and Martian Pain" by David Lewis, in Readings in Philosophy of Psychology, 1980.
Baggini, J., The Pig That Wants to Be Eaten, 2005, p. 202.
Baggini has simplified the discussion considerably here by only looking at half of the original thought experiment from David Lewis. This story only concerns itself with what Lewis called "mad pain" — the case where pain doesn't act the way it does for the rest of us. As Baggini describes this:
The story of David's "mad pain" is an attempt to play with the variables associated with pain to see which are essential and which are incidental. The three main variables are private, subjective experiences; typical causes; and behavioural responses. Mad pain has only subjective experience in common with ordinary pain; its causes and effects are quite different. If it is nonetheless accurate to describe mad pain as pain, then we should conclude that it is the subjective feeling of being in pain which is the essence of pain. Its causes and effects are merely incidental, and could be different from what they usually are. ... The rub of the issue, however, concerns the relation between the inner and the outer. It might seem easy to say that pain is defined by how it feels to the sufferer, and that this has an essential link to behaviours such as avoidance and grimacing. But this solution is too quick. For if pain really is a feeling, then why should it be inconceivable to experience pain without any of the associated behaviour? It's no good just saying it must manifest itself in some way; you need to say why it must do so. Until you can, mad pain remains a possibility.
That's easy enough. First, let's agree that pain is a feeling. Since David in the thought experiment "did not find the sensation of this pain at all unpleasant," reader Pedrag Selimanovic commented:
It's not pain then. I know that some people experience pleasure while experiencing (some type of) pain but the unpleasant part is actually a real and important aspect of it.
That's true. The feeling is necessary, as illustrated by the people who don't feel pain who often suffer severe self-inflicted injuries and premature death as a result of that deficiency. So then what about Baggini's main question: why must pain be associated with typical behaviours? In general, that is exactly what does happen. (Hence, they are called typical.) Explaining why, from an excellent evolutionary standpoint, reader Steve Willey commented:
Pain is a survival mechanism to bring priority awareness of bodily damage to conscious thought to facilitate corrective action. It's essential to survival for all animate life, insects included. Depending on severity it overrides other brain processes as an emergency signal for needed avoidance action. In brain damage as described, its function / manifestation has been modified and purpose defeated.
From the facts given in the thought experiment, this is why David's reactions to his "mad pain" may be possible but they are problematic. The fact that his "shoulders would shrug, eyebrows lower and rise in quick succession, or his elbows flap out, making him look like a chicken," all means that his specific pain response has been rendered defective. However, this alone does not mean that he does not feel pain. Pain does not need to "have an essential link to behaviours such as avoidance and grimacing," as Baggini pointed out. Think of the self-immolating monk in the picture at the top of this post. Surely, he felt extreme pain. His nociceptive neurons must have been firing with the greatest intensity they were capable of. But in one of the most extreme acts of courage and self-control we know of, the monk expressed no reaction to it. We can explain his behaviour by my earlier comment that although pain is meant to keep us alive, the definition of "us" is changeable and can be extended to others. In this case, the monk performed his act of protest for the purpose of keeping a larger "us" alive than merely himself. We humans can do that.
So yes, mad pain is possible. Among the three main variables for pain, two of them—typical causes, and behavioural responses—have exceptions. Only the third variable—the private, subjective experience—is necessary for pain. Our shared evolutionary histories mean those private experiences are extremely likely to be shared, but sane pain doesn't have to look normal, and truly mad pain will lead to failure with respect to the true goal of pain, which is to lead us away from extinction. That's the answer to Baggini's version of the thought experiment.
But what about the original experiment from Lewis that Baggini cited? While we're here, I ought to try and address that as well. As the title of his paper makes clear, Lewis discussed both mad pain and something else he called Martian pain. Just to reiterate the first type (as it was originally written) and then contrast that with the second, here's a nice summary of Lewis's two forms of pain:
1) The being with "mad pain" is a human being, except when his brain is in a state of pain, his mind turns to mathematics and he begins to snap his fingers. He is not at all inclined to prevent the pain from occurring. Lewis ultimately goes on to explain that pain is relative to a species, implying that the man who exhibits mad pain is essentially an exception. In Lewis' words, "In short, he feels pain but his pain does not at all occupy the typical causal role of pain."
2) A being with "Martian pain" is not human but, when subject to pain, will react in the same way that humans do. He is strongly inclined to prevent whatever stimulus is causing discomfort. However, the physical explanation of Martian pain is different from that of human pain. He has a "hydraulic mind" and pain is identical with inflation of cavities in his feet. In Lewis' words, "In short, he feels pain but lacks the bodily states that either are in pain or else accompany it in us."
Why introduce these two types of pain? As Lewis states in the original paper: "If I want a credible theory of mind, I need a theory that does not deny the possibility of mad pain, [and it also] needs to make a place both for mad pain and for Martian pain." We've already checked off the first requirement, agreeing to the possibility of mad pain, but before we get to why Lewis thinks his two types of pain are two horns of a dilemma that pose problems for any coherent theory of mind, I want to place this in some context. Bear with me for just a second. (Or skip to the next asterisk if you already know all the ins and outs of the Philosophy of Mind.)
Philosophers have proposed loads and loads of theories of mind in their attempt to solve the mind-body problem. I've already briefly described the two major schools of thought on this—dualism and monism—but there is a third minor camp called mysterianism that I should mention too. That idea claims that since we haven't solved it yet, it seems likely that we must be biologically unable to solve the mind-body problem, sort of like the way that mice lack the symbolic brain apparatus to ever know particle physics. However, since our scientific inquiries into the universe in general have not slowed to a halt, and since neuroscience in particular is still a long way away from a complete mapping and understanding of the brain, I'm going to dismiss mysterianism until we're done learning. As for dualism vs. monism, let's first see a quick list of the options for each that I found:
- Monism: physicalist (behaviourism, identity theory (type or token, or reductive materialism), functionalism, non-reductive physicalism, weak emergentism, or eliminative materialism); non-physicalist (idealism (pluralistic, solipsistic, or absolute)); or neutral monism.
- Dualism: interactionist dualism, psychophysical parallelism, occasionalism, property dualism (strong emergentism, epiphenomenalism, non-reductive physicalism, or panpsychism), dual aspect theory, experiential dualism, or hylomorphic dualism.
So, drawing down through the list of choices, first of all I'm a monist. From within that group, physicalists argue that "only entities postulated by physical theory exist, and mental processes will eventually be explained in terms of these entities as physical theory continues to evolve." I agree with that. Searching further down, reductive materialism (within identity theory) is the one that argues that "a mental state is well defined, and that further research will result in a more detailed, but not different understanding." Due to my epistemological stance that knowledge can only ever be: justified, beliefs, that are surviving, I'm comfortable agreeing to this and waiting for science to uncover any necessary changes. Continued progress in neuroscience has helped to clarify some of the mind-body issues (e.g. the belief by Descartes that the mind exerted control of the brain through the pineal gland was thrown out long ago), but without knowing how life first arose or what consciousness really is, the exact answer to the mind-body problem is for now uncertain.
Getting back towards our thought experiment, but still clarifying its location within the vast discussion of the mind-body problem, I must explain that David Lewis is a functionalist. So he, like most of us, is also a monist and also a physicalist, but of a slightly different flavour. Functionalism is a theory of the mind:
...developed largely as an alternative to both the identity theory of mind and behaviorism. Its core idea is that mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role – that is, they have causal relations to other mental states, numerous sensory inputs, and behavioral outputs. Functionalism is a theoretical level between the physical implementation and behavioral output. It is only concerned with the effective functions of the brain, through its organization or its "software programs".
In Lewis' abstruse words, functionalists "speak of the place of pain in the causal network from stimuli to inner states to behavior." In my simpler words, functionalists think the function of pain is necessary and sufficient to identify pain. Got it? Good. Now back to the dilemma.
In "Mad Pain and Martian Pain," Lewis sets up a supposed difficulty for simple theories of mind, and then defends his functionalist position as able to overcome the supposed difficulty. As he himself explains it in the original paper:
"A credible theory of mind needs to make a place both for mad pain and for Martian pain. Prima facie, it seems hard for a materialist theory to pass this two-fold test. As philosophers, we would like to characterize pain a priori. As materialists, we want to characterize pain as a physical phenomenon. ... But the lesson of mad pain is that pain is associated only contingently with its causal role, while the lesson of Martian pain is that pain is connected only contingently with its physical realization. How can we characterize pain a priori in terms of causal role and physical realization, and yet respect both kinds of contingency? A simple identity theory straightforwardly solves the problem of mad pain. It goes just as straightforwardly wrong about Martian pain. A simple behaviorism or functionalism goes the other way: right about the Martian, wrong about the madman. ... It seems that a theory that can pass our test will have to be a mixed theory. It will have to be able to tell us that the madman and the Martian are both in pain, but for different reasons: the madman because he is in the right physical state, the Martian because he is in a state rightly situated in the causal network."
Here we go again, where a philosopher has gotten himself into an unnecessary battle because he insists on trying to think his way to knowledge alone. Lewis asks, "how can we characterize pain a priori"? Well, we can't. If Lewis would drop the latin jargon for simpler language, his argument might be easier to see through. A priori literally means "from before," but is taken more broadly as an adjective "relating to or denoting reasoning or knowledge which proceeds from theoretical deduction rather than from observation or experience." Pain cannot be theoretically deduced (a priori) without observation or experience, because pain is precisely a reaction to observation and experience. Descriptions of pain must reflect the evolutionary history of experience for the creature in pain being considered. The "simple identity theory" that Lewis finds flawed is one that would define pain as the identity of a single specific physical state. Something like "pain = firing of nociceptive neurons." But this is a straw man, as if anyone would think all pain in the universe could be defined this way. Looking at the list of painful and pleasurable stimuli and responses in my opening paragraph, we can agree that "pain" is a complex category of things rather than a simple individual thing. Its general function for survival must be understood, but then its physical identities for specific instances can all be investigated and described. To search for a single physical phenomenon for "pain" is a category error; it's like looking for a "university" rather than all the buildings and people that make one up.
So that explains why Lewis' argument is flawed from the start against my flavour of physicalism (reductive materialism within identity theory), but let's take a quick look at where he ended up. How does Lewis go on to define pain using his functionalist viewpoint? Here is the relevant passage:
Our view is that the concept of pain, or indeed of any other experience or mental state, is the concept of a state that occupies a certain causal role, a state with certain typical causes and effects. It is the concept of a state apt for being caused by certain stimuli and apt for causing certain behavior. ... It is the concept of a member of a system of states that together more or less realize the pattern of causal generalizations set forth in commonsense psychology. ... In short, the concept of pain as Armstrong and I understand it is a nonrigid concept. Likewise the word "pain" is a nonrigid designator. It is a contingent matter what state the concept and the word apply to. It depends on what causes what. The same goes for the rest of our concepts and ordinary names of mental states.
Well that answers that doesn't it?! I underlined all the weasel words in Lewis' description of pain, which make it pretty clear that he hasn't done much to actually define pain....even though reading his paper sure caused me some pain!
After considering all of this, I'd like to end with some thoughts on pain that came to me while writing this post. It is obvious that we humans feel pain when flesh and bones are torn apart, but perhaps we can feel physical pain when neuronal connections are torn apart as well. When something we've "known" for a long time is undone, this is what must literally happen inside our brains. This would explain the observation I quoted last week from Edgar Schein who said that any challenge of a basic assumption will release anxiety and defensiveness. Such challenges painfully tear our minds apart. If that is true, this would also explain why philosophy can often be painful to read, and why my own new work is particularly painful for most. Ripping off the duct tape that holds most worldviews together though seems much more preferable to me than feeling the continual anxiety that seems to arise when most worldviews are faced with evidence from the real world. So thanks for working through such pain with me. It's a pleasure to have you here.