Much has been said about the use of the imagination in philosophy. You find imaginative thought experiments all over the place. (Philosophical zombies and Mary the colour scientist are good examples.) It dates back to Descartes. However, the use of the imagination was reprised by Saul Kripke and others in the early 1970s. Nowadays, philosophers like David Chalmers and Philip Goff extensively rely on what they call “conceivability”. (Conceiving and imagining are distinguished from each other by some philosophers.)
“All arguments against the identity theory which rely on the necessity of identity, or on the notion of essential property, are, of course, inspired by Descartes’ argument for his dualism.”
— Saul Kripke, Note 19 of ‘Identity and Necessity’.
The American philosopher Saul Kripke worked on his (to use his own words) “Cartesian intuitions” when he tackled the mind-body problem. Many of those intuitions were about what is, and what is not, logically possible.
Kripke is a very relevant philosopher to bring into any debate about the use of the imagination — or, as it’s often classed today, conceivability — within philosophy. That’s because he seems to have held two contrasting arguments: (1) One argument is used to advance his position on the acceptable use of the imagination in philosophy. (2) The other argument is used to criticise the use of the imagination by his critics.
In the first instance, Kripke informed his audience about an act of imagination which actually misleads us (metaphysically speaking). He wrote:
“[W]e thought erroneously that we could imagine a situation in which heat was not the motion of molecules. Because although we can say that we pick out heat contingently by the contingent property that it affects us in such and such way.”
Kripke also offered us the examples of imagining that water is not H₂O, as well as the case of a person conceiving of a true mathematical theorem to be false or false theorem to be true. (Kripke gave the example of Goldbach’s conjecture.)
On the other hand, Kripke also believed that imagination (or what we can conceive) can tell us something very important about various philosophical issues. In Kripke’s own words:
“[J]ust as it seems that the brain state could have existed without any pain, so it seems that the pain could have existed without the corresponding brain state.”
Kripke stressed our ability to imagine a pain state without its correlated brain state (formerly characterised as the “firing of C-fibres”). Thus, Kripke concluded (to paraphrase):
If we can imagine mental states without their correlated brain states, then such states are possible.
Alternatively put, Kripke was arguing that there’s no necessary identity between mental states and brain states.
Misimagining
Kripke was aware that philosophers criticised his emphasis on both the imagination and “intuitions”. However, he didn’t say much about either. He did tell us that a “materialist” (it needn’t be a materialist!) “has to show that these things which we can imagine are not in fact things we can imagine”. The Cartesian intuitionist is imagining something when he imagines, but the argument in the following is that he’s not imagining what he believes he’s imagining. He’s not imagining, for example, disembodied pain. So no one is claiming that Kripke didn’t imagine something that worked as a substitute (or a surrogate) for what he believed he was imaging.
Of course, Kripke might well have asked the following question: How do you know that I’m not imagining this? However, his critic could have replied: How do you know that you are? How do I know that you are?
But there’s a little problem here. In the same paragraph Kripke says that the materialist
“has to hold that we are under some illusion in thinking that we can imagine that there could have been pains without brain states”.
This is very different to imagining an actual pain without a brain state. Loosely, perhaps anyone could imagine a pain without a brain state… However, what is being imagined in these instances? Not an actual pain, but some kind of vague possibility that doesn’t involve imagining an actual pain without a brain state.
Disembodied Pains?
What is it to “imagine my pain existing even if the state of the body did not”? Drawing on some of Kripke’s own arguments, doesn’t the imaginer need to literally be in pain in order to imagine his pain? After all, when it comes to pain, many have argued that there’s no reality-appearance distinction to be made between imagining a pain and actually being in pain [see here]. If that’s the case, then no one imagines pain existing even if the state of the body did not simply because no pain is imagined in the first place.
All that said, the words “imagine my pain existing even if the state of the body did not” aren’t clear. Arguably, in this instance an actual pain needn’t be imagined at all, let alone felt. In that case, then, what is imagined? The behavioural manifestations of pain? That obviously wouldn’t work for Kripke’s argument. So once the body and brain are (imaginatively) erased (along with the behavioural manifestations of pain), then what on earth is left?
Again, what exactly did Kripke imagine when he imagined a bodyless pain? Did his pain float free in the ether? In this case, did Kripke imagine, say, a tooth ache without any teeth, or a headache without a head?
What about psychological pain? Take depression. Even in this case depressive pain is intimately linked to many physiological symptoms and changes. In other words, psychological pain isn’t either abstract or disembodied: it is at least partly physical. (Some would say entirely physical.)
Kripke went further:
“We can perhaps imagine my not being embodied at all and still being in pain, or, conversely, we could imagine my body existing and being in the very same state even if there were no pain.”
Kripke supposedly imagined two things here. (1) He imagined “not being embodied at all”. (2) He imagined being in pain without having a body. As already stated, to imagine a pain is to be in pain. (What is imagined if there is no actual pain?) Kripke imagining being disembodied is also problematic. What is it that he imagined when he imagined himself disembodied? What was it, precisely, that was disembodied? The “I” or the “soul”? (Berkeleyan idealists touch on something similar in response to someone saying that he could imagine a tree falling without anyone around to hear it. Berkeleyans respond by arguing that all the imaginer is doing is imagining himself being there, perhaps in some vague supposedly disembodied state. Thus, he surreptitiously imagines what he would hear — with his physically-embodied ears, etc. - when the tree is falling.)
In a very loose sense, Kripke might have “imagine[d] [his] body existing and being in the very same state even if there were no pain”. Sure. Kripke could also have imagined his body existing and being in the same state and yet having a pain in a completely different area of the body. He could have even imagined being in the same physical state and being a (philosophical) zombie…
However, no actual pain was ever imagined.
So what was imagined? The behavioural manifestations of being in pain? They would have been easy to imagine.
Imagining Different Inventors of Bifocals
Kripke’s imaginative abilities are used across the board in his paper ‘Identity and Necessity’. For example, Kripke — and everyone else — could have easily imagined someone else inventing bifocals other than Benjamin Franklin. Here all Kripke needed to do was to use his… imagination. After all, I can imagine Hitler inventing bifocals. I can also imagine bifocals never having been invented at all.
Imagination also comes to the rescue in Kripke’s case against the American philosopher David Lewis. Kripke told us that Lewis imagined Richard Nixon himself inventing bifocals or “getting [G. Harold] Carswell through”. Apparently, Lewis believed that it was (is?) the actual Nixon who did these things at other possible worlds. However, Kripke argued that Lewis only imagined Nixon’s “counterparts”, not “our Nixon”.
Another of Kripke’s examples is a philosophical opponent imagining this lectern being made of ice, rather than wood. Kripke argued that what his opponent was actually imagining was not this lectern, but another one that existed in a “counterfactual situation”. However, if one is an essentialist like Kripke, then this lectern must be made of wood. Regardless of the truth of that essentialist position, what was it that was being imagined when Kripke’s opponent imagined this lectern being made of ice? Kripke argued that he didn’t imagine this lectern being made of ice, but a lectern being made of ice. That is, a lectern that looked the same as the wooden lectern in all respects… except for being made of wood.
Now to ram the point home. We see the same scenario played out when Kripke discussed Hesperus and Phosphorus. Kripke told us that his philosophical opponents “may mean that they can actually imagine circumstances that they would call circumstances in which Hesperus would not have been Phosphorus”. Thus, Kripke made the same point that no such thing was actually imagined. Indeed, Kripke was explicit about his own case against these imaginers. For example, he argued that his opponents “thought erroneously that [they] could imagine a situation in which heat was not the motion of molecules”. Kripke is stronger elsewhere when he used the word “mis-imagined”. That is, he argued that the imaginers believed that they’d imagined scenario x, but they didn’t. They actually imagined some surrogate or counterpart of x.
Yet, ironically, the same kinds of thing can be said about Kripke’s own use of his imagination when he claimed to have imagined his own disembodied pain.
Note: Phantom Pains
It’s worth stressing the case of “phantom pains” — which belong to phantom parts of the body — here. In this case, the sufferer isn’t consciously imagining pain as part of a Cartesian thought experiment. Instead, he’s actually feeling pain regardless of his conscious acts or will. (How could we know that?) What’s more, even phantom pains require brain states. And phantom pains are actual pains (although this is hard to establish).
Oddly enough, Descartes himself mentioned phantom limb pain [see here]. He argued that because the mind is connected to the body at the pineal gland, then it’s possible that the pineal gland might be affected by stimuli which didn’t correlate with any actual parts of the body. Yet even in this case of a phantom pain that was part of the “substance” that is the mind, it was still connected to the body via a part of the brain.
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