1. Introduction
The mind is whatever is ultimately bearing our conscious experiences. Substance dualism is the view that the mind is a nonphysical object. In what follows, I am going to argue that our moral intuitions about the inherent value of our minds strongly imply that our minds are nonphysical objects.
First, I will clarify what substance dualism of the kind I am seeking to support here involves. Second, I will outline a few assumptions I will be making about morality. Third, I will say something about moral intuitions. Fourth, I will present the moral argument. Finally, I will consider some objections before concluding.
2. Substance Dualism
There is no uncontroversial definition of a physical object. However, we have a pre-theoretical understanding of the concept that proposed definitions are trying, at least approximately, to capture. For instance, my mug is a physical object, and it is currently inside my house, which is also a physical object. However, there are serious limits to what my mug can be inside. It cannot be inside—wholly inside—something smaller than it or inside something solid. Yet, the kind of object our moral intuitions imply is bearing our conscious experiences is one apparently capable of existing inside any other thing at all and all by itself. So, it is a kind of object that has no size or mass. It seems no abuse of the term to describe such an object as nonphysical. Thus, if I am correct, our moral intuitions imply that our minds are nonphysical objects in this pretheoretical sense.
3. Moral Assumptions
I am going to have to make a few assumptions about morality. These are not entirely uncontroversial (that would be nigh on impossible). However, they are widely endorsed and are less controversial than their alternatives. The first assumption is ethical realism. This is the combination of two claims. The first claim is that the truth or falsity of an ethical claim is not constitutively determined by anyone's feelings or beliefs about it.Footnote 1 The second claim is that at least some ethical propositions are true. That is to say, it is not just that there appears to be an objective ethical dimension to the universe. There actually is one.
We might think of the moral landscape as being in some ways analogous to the physical one. Our five senses give us the impression of an objective physical landscape, but the sense impressions do not compose it. Similarly, most of us get the impression, via what tend to be termed ‘moral intuitions’ (about which more shortly), of an ethical landscape. However, moral intuitions do not compose the ethical landscape. Moral intuitions are a kind of appearance. They represent there to be an objective moral dimension, just as our sense reports represent there to be an objective physical dimension.
Some claim that moral intuitions are actually a species of belief, distinct from the others in that they are justified by our understanding their propositional contents (Audi Reference Audi2004: 33–36).Footnote 2 It does not really matter to my case if one construes them as such, for I think my case could still be made with small adjustment. However, I am going to stick with construing moral intuitions as appearances because that is what they appear to me to be. Just as sometimes things appear visually to be a certain way (the stick in the water appears bent), but I do not believe what seems to be the case, so too sometimes something appears intuitively wrong; yet, I do not believe it to be wrong. The intelligibility of such statements suggests that moral intuitions and moral beliefs are different sorts of mental states. In this respect I follow others, such as Huemer (Reference Huemer2005) and Killoren (Reference Killoren2010: 2, fn. 1).
Another assumption I will be making is reliable access. I assume that my five senses provide me with fairly reliable (though far from perfect) access to the physical dimension. I am going to assume that moral intuitions provide us with fairly reliable access to the ethical dimension.
Some of what I have said above might make it sound as if I am assuming our faculty of moral intuition to be a sixth sense. We do sometimes talk of a ‘moral sense’. However, such talk should not be taken literally. For instance, no one thinks we can, by moral intuition, detect whether we are being lied to, or whether there is an innocent in the building we are proposing to destroy. The manner in which our moral intuitions give us insight into the ethical differs in an important way from how our sensory appearances give us access to the physical. I will say more about this in the next section.
4. Intuitions
Not everything we know about the universe derives from the reports of our five senses. For instance, does the universe contain any objects that are red all over and green all over at the same time? No, it seems clear to most of us that it does not. But how do we know that? It is implausible to suggest that it is just because we have never seen any such things. It appears necessarily to be true that there aren't any. By contrast it appears merely contingently true that, say, there are no unicorns. Unicorns could ‘in principle’ exist and searching for some is not wholly misguided in the way that looking for some simultaneously red and green things does seem to be.
Some might propose that the claim that ‘nothing can be red all over and green all over at the same time’ is true by definition. But as Huemer points out:
It is not enough just to make this kind of claim; to make good on it, the empiricist must produce the definitions of ‘red’ and ‘green’ together with the actual derivation, from those definitions, of the statement ‘Nothing can be both red and green’. No one has done this; indeed, the whole project seems stymied at stage one by the absence of any analytical definition of either ‘red’ or ‘green’. It is here that some are tempted to appeal to scientific knowledge about the underlying nature of colors to construct definitions (saying, for example, ‘red is the disposition to reflect such-and-such wavelengths of light’). But this approach leads to the absurd consequence that, say, 300 years ago, people were in no position to know whether it was possible for a red object to be green—indeed, did not even understand the meanings of those words—since they did not know the scientific theory of colors. (2005: 112–13)
It seems, then, that it is not by sight, sound, smell, taste, or hearing that we know there are no simultaneously green and red objects. Rather, we know this by intuition: rational intuition.
We intuit a lot. We intuit that if we are thirsty and the mug in front of us contains water, then we have some reason to take a drink from it. We do not see such reasons with our eyes or hear them or taste, smell, or bump into them. It is not that we do not know what they look like or feel like. Rather, normative reasons (reasons to do and believe things) are just not in the looking-a-way or feeling-a-way business. That is to say, they appear positively to be textureless, shapeless, colorless, soundless, and tasteless. We do not sense their presence; we intuit it.
Note that all intellectual inquiry presupposes that there are reasons to believe things—and so assumes that there is a normative dimension to the universe—for evidence in support of a proposition just is a consideration that provides a reason to believe something. As Huemer puts it:
Intuitions are not some exotic, theoretical entities invented by a few philosophers. They do not merely play some minor, recherché role, such that we could excise them and our intellectual life would go on pretty much the way it does now. Nor is there some alternative, intuition-independent methodology being implemented by some other group of philosophers. (2005: 119)
To forestall possible misunderstandings, note that there is no suggestion—no suggestion in anything I have said above, anyway—that intuitions are infallible. I have suggested that intuitions give us insight into necessary truths about the universe. Footnote 3 By definition, it is not possible for a necessary truth to be false. But it is possible for an intuition to be inaccurate. So, it is possible for something to appear to be a necessary truth, yet not be one. The difference (in part anyway) between rational intuitions and sense reports seems to concern the nature of the truths they give us insight into, rather than their reliability. That is why we have to build our theories of everything carefully, attempting to achieve a best overall systemization of our clearest, widely corroborated sense impressions and rational intuitions.
Note also that there is no suggestion that if something is necessarily true, we will intuit it to be so. There are, we are told, colors it is beyond our faculty of sight to detect. By the same token, perhaps there are many necessary truths beyond intuitive detection. Thus, although intuitions provide insight into necessary truths about the universe, there is no special reason to think they do so with total accuracy or comprehensively.
To get back to morality: virtually all moral realists hold that moral truths are among the necessary truths about our universe (see Coons Reference Coons2011; Huemer Reference Huemer2005: 122; Murphy Reference Murphy2011: 36–37). It is not just that Xing in circumstances S at time T happens to be wrong. It is necessarily wrong, if it is wrong at all. And so, as with other necessary truths, we know of moral truths not by sight or sound, touch, taste, or smell, but by intuition.
As already noted, we cannot by moral intuition detect if we are being lied to or if there is an innocent person in the building we’re about to demolish. These are contingent matters. But we can tell by moral intuition that if we are being lied to in such-and-such circumstances, then we are necessarily being wronged, or if the building has an innocent person in it, then it would be necessarily wrong to demolish it. We might usefully picture our faculty of moral intuition (and our faculty of rational intuition more generally, though I will focus just on moral intuitions in the remainder) as a kind of crackly phone line to an ethical help desk (a help desk within the larger Reason Inc.). The operators have information about what is necessarily true, including the necessary connections that exist between the nonmoral and moral. But they have no information about what is contingently true. That is information we must provide on every occasion. As with most help desks, not all operators are well-trained or competent, and the lines aren't always clear. Nevertheless, clear, confident replies that are widely corroborated by what other people's help desk operators say about similar cases have considerable probative force.
Sometimes our help desk operators give us no clear response. This is where thought experiments are useful. In a thought experiment we describe a hypothetical situation to our help desk operators, one that seems in some ways similar to the case at hand and about which we hope to get a clearer response. Note, the fact the verdict is about an imaginary case should not, in principle anyway, make any real difference to the reliability of the response. For the ethical help desk operators do not have any information about contingent truths beyond what we tell them on any given occasion. Thus, other things being equal, what they tell us about imaginary cases will be just as reliable as what they tell us about actual cases. Of course, we may have difficulty properly and vividly representing an imaginary situation, but that's what the ‘other things being equal’ clause is in there to cover.
In summary, then, moral intuitions are a species of rational intuition that, like other rational intuitions, provide us with fairly reliable (but far from perfect or comprehensive) insight into necessary truths about the universe. And, other things being equal, moral intuitions about thought experiments are just as reliable a source of insight into such necessary truths as moral intuitions about actual cases.
5. Subjects and Inherent Value
We are bearers of conscious experiences, of feelings, perceptions, thoughts, and memories. Most of us have the powerful moral intuition that we have moral value, that is to say, we are owed a degree of respect and good will from others. Furthermore, it is intuitively obvious to most of us that this moral value is not wholly determined by the value of the conscious experiences we are undergoing. This is not to claim that our moral value cannot be affected by the kinds of conscious experience we are undergoing. Someone who thinks nasty thoughts, wills nasty ends, and so on can perhaps come to be worth less than someone who does not. The point remains, however, that we need already to have some moral value in order that the presence of certain conscious experiences in us can subsequently diminish it.
Of course, conscious experiences—many of them—are morally valuable. Pleasure is normally morally valuable. However, intuitively our moral value does not go up and down according to how much pleasure we are undergoing. I did not become slightly less deserving of respect when I stubbed my toe this morning, and I do not cease to be morally valuable when I am unconscious. So, morally speaking it appears—and appears very strongly to virtually all of us—that we, bearers of conscious experiences, have a moral value that is not constitutively determined by the value of the conscious experiences we are undergoing. In other words, our intuitions—our ethical help desk operators—tell us that if we are bearers of conscious experiences, then we, the objects bearing such things, have a moral value that is independent of the value of those experiences. We, the minds, the containers of conscious experiences, have inherent moral value (I take the term ‘inherent value’ from Regan Reference Regan1983).
Exactly how much inherent moral value we have, what else can or cannot contribute to our moral value, how to show respect for that value, what to do in conflict situations, and to what extent our overall value can be diminished by what we do and undergo are fiendishly complicated matters. Thankfully, these are all issues that can be left open here. All that matters for my purposes is that it is intuitively obvious that we, the bearers of conscious experiences, have a significant inherent moral value.
In fact, even less than this is required. For some may hold that not all bearers of conscious experiences have inherent value (or much inherent value). Perhaps it is only persons capable of bearing certain sorts of conscious experiences that have significant inherent value, whereas those not capable of doing so either have no inherent value or have considerably less. Again, this is a matter we can put to one side, for my argument does not require us to take a stand. All that is needed for my case to stand up is the intuition that bearers of at least some kinds of conscious experiences have a significant inherent value, a value that is not reducible to the value of those experiences. Nevertheless, for ease of argument, I will talk just of bearers of any conscious experiences having significant inherent moral value.
Given that moral intuitions provide insight into necessary truths about the universe, it would seem that it is a necessary truth that bearers of conscious experiences have inherent value. This implies it is a necessary truth that conscious experiences are being borne by a particular kind of object, one the help desk operators know to have a significant value that is not reducible to those experiences. Therefore, it would appear to be a necessary truth that conscious experiences are borne by a particular kind of thing and a necessary truth that such things have significant inherent moral value.
Nothing said so far implies that the ultimate bearer of our conscious experiences is a nonphysical thing. Perhaps it is a necessary truth that conscious experiences are borne by complicated lumps of electrified meat and that complicated lumps of electrified meat have significant inherent value. Thus, when we phone operators and tell them that we are undergoing conscious experiences, they know that we must be a complicated lump of electrified meat and know that such things have inherent moral value.
But now engage in the following thought experiment. Imagine you have no physical body whatsoever. When you look down, you see nothing. When you look into a mirror, you see nothing reflected back apart from the wall behind you. Moreover, you find that you can glide through walls and other physical obstructions and no one else can detect your existence by any of the five standard senses. In other words, imagine finding that your conscious experiences are not being borne by any physical body at all. Represent this possibility to an ethical operator. What does he/she say? In other words, what are our moral intuitions about our moral worth if it should turn out that we lack anything that might, pretheoretically, be described as a physical body?
The operators at the help desk say (with as much confidence as ever) that if that truly is our situation, we still have inherent value. It appears intuitively obvious that even if what I have been taking to be my body is a clever hologram, I am still owed the same degree of good will, respect, and so on. If my body is a hologram, it is still wrong for you to fail to fulfill your promises to me or to speak ill of me behind my back. Just as my inherent moral value does not go up or down according to whether I am miserable or happy, it does not go up or down according to whether I have a physical body or not. Someone who held otherwise would be guilty of what might be termed ‘bodyism’. So, our moral intuitions tell us, loud and clear, that we have inherent moral worth irrespective of whether we possess a physical body. This, I hold, strongly implies that we, the bearers of inherent value, are not physical bodies.
It might be objected that the apparent irrelevance of an object's shape, size, and color to its possession of mass does not entail that the possessor of mass lacks color, shape, and size. And so, by extension the apparent moral irrelevance of our mind's shape, size, and color does not entail that the mind lacks a shape, size, and color.Footnote 4 In reply, first note that the thought experiment above implies that it is irrelevant whether we—the objects bearing inherent value—even have a shape, size, mass, or color at all, not just what shape, color, or size we have. This still does not entail that our minds lack such things (which is just as well, for if it turns out that our conscious experiences are being borne by physical things, we do not want to be forced to have to reject our intuitions about our inherent moral value), but it does strongly imply it.
Consider: if it was a necessary truth that conscious experiences are borne by physical objects of some sort, then upon representing ourselves to have no physical bodies whatsoever one would predict unclear, wavering, confused replies from our ethical operators. From their perspective, we would have told them is that an object with inherent value is present and not present at the same time. However, our moral intuitions are clear, confident, and unwavering. That is, our moral intuitions are telling us, loud and clear, that it is not a necessary truth that conscious experiences are borne by physical objects.
It still remains possible, consistent with our moral intuitions being what they are, that our conscious experiences are being borne by something physical. For it could be a necessary truth about conscious experiences that they are either borne by a certain sort of physical object or by a nonphysical object, and the inherent moral value of both happens, coincidentally, to be exactly the same. Or it could be that the value-conferring property is ‘being an object capable of being the ultimate bearer of conscious experiences’, a property that might be possessed by brains and nonphysical objects alike. If this were the case, then we would have an explanation of why our ethical operators are indifferent to whether we represent ourselves to have a body or not. Yet, other things being equal, these are not the most reasonable explanations of our moral intuitions.
Imagine a detective at a crime scene proposing that the trail of bloody footprints leading away from Janet's body were left by two assailants who, coincidentally, were wearing exactly the same sorts of shoes and walking in each other's footsteps. This is possible, but absent powerful independent reason to think that there were two assailants, it is not a reasonable thesis. Likewise, the most straightforward explanation of our moral intuitions about the inherent moral value of our minds is that there is one kind of object that can bear conscious experiences—a nonphysical one—and that it is necessarily true that such objects have significant inherent value. Proposing that there are two kinds of object capable of bearing conscious experiences—brains and nonphysical objects—would be an ad hoc and unnecessarily baroque explanation of our moral intuitions. It is simpler to propose that our ethical operators are indifferent to whether we represent ourselves to have a body or not because they know that the kind of thing that bears conscious experiences is one the presence of which is compatible with us possessing a body and also compatible with us not possessing a body. Thus, other things being equal, our moral intuitions provide prima facie evidence that conscious experiences are borne by a nonphysical object and that it is a necessary truth that this sort of object has significant inherent moral value.
For an analogy: take the debate over the kind of control needed for morally responsible agency. Suppose we could find an uncontroversial way of representing causal determinism to be true and an uncontroversial way of representing causal indeterminism to be true. Imagine we find that our moral intuitions about an agent's moral responsibility remain the same for both representations. That is to say, our ethical help desk operators appear indifferent to whether we have represented determinism as true or false. Virtually everyone would take this to be powerful evidence that the kind of control necessary for moral responsibility is of a sort that is compatible with determinism and indeterminism. Our moral intuitions cannot tell us whether determinism or indeterminism is true, but they can tell us that it does not matter. Note that, other things being equal, it would not be reasonable to conclude that there are two quite different sorts of control that happen to be equally sufficient for responsible agency, with one requiring determinism and the other requiring indeterminism (and thus that determinism provides one but precludes the other and vice versa). This would be consistent with our moral intuitions, but it would be a perversely baroque explanation of them.
Likewise, our moral intuitions about our inherent value and their indifference to whether we represent ourselves to have a body or not imply that the kind of object that bears our conscious experiences is of a sort that is compatible with our having a physical body and also compatible with our not having one. And we can represent ourselves to have any kind of body whatever, no matter how big or small, or no body at all, and our intuitions remain the same. Our moral intuitions thus imply that the kind of object that bears conscious experiences can be inside any kind of physical body whatever or can exist by itself. Pretheoretically, an object like that seems to qualify as nonphysical. Thus, our moral intuitions are implying that we, bearers of conscious experiences, are such objects.
At this point it might be objected that even if we have clear moral intuitions about a situation, this does not establish that the situation involves something metaphysically possible. For instance, clear moral intuitions about what to do in a situation involving backward time travel would not establish that backward time travel is metaphysically possible. So why should intuitions about bodiless bearers of conscious experiences be taken to imply that it is metaphysically possible (and actual) that the bearers of our conscious experiences are nonphysical objects?
In reply I would point out that my argument does not assume that clear moral intuitions about a case automatically imply that the case represents a metaphysically possible situation. Moral intuitions tell us about the morally relevant features of a situation. They are moral intuitions. It is an ethical help desk. Accordingly, a situation in which all morally relevant features are coherently represented should continue to elicit clear moral intuitions even if the morally irrelevant features could not possibly obtain. If we represent to our faculty of moral intuition a scenario we have independent reason to think could not possibly obtain—such as one involving backward time travel—and it continues to elicit clear moral intuitions, this implies not that backward time travel is metaphysically possible, but that the temporal location of an act is morally irrelevant (or alternatively, that our moral intuitions can only provide insight into the moral lay of the land at the present time). By contrast, it is obviously morally relevant what kind of object is bearing our conscious experiences for it bears inherent moral value.
In summary, our moral intuitions imply that our conscious experiences are ultimately borne by a nonphysical thing: a thing that can be inside any physical thing whatsoever (for it does not seem to matter what kind of physical thing you represent your conscious experiences as being inside); yet, this thing can also exist entirely by itself.
6. Objections
I anticipate two general kinds of objection. The first takes issue with the strength of moral evidence, holding that moral evidence is very weak evidence or not really ‘evidence’ at all. The second line of objection holds that there are strong independent reasons to think substance dualism is false and that these easily outweigh any positive case provided by our moral intuitions.
Obviously, there is a real limit to what I can say in response to such general criticisms. But with regard to the first: why think moral evidence is weak evidence? The clear and widely shared intuition that nothing can be simultaneously green all over and red all over is powerful evidence that there is nothing simultaneously green all over and red all over in the universe. The clear and widely shared intuition that if I am thirsty and the glass in front of me contains water, then I have some reason to take a drink from it is powerful evidence that this is indeed the case. On the face of it, there is no reason to treat moral intuitions—clear, widely shared ones—any differently.
It might be objected that divergent moral intuitions across time and space call into question their reliability. In reply I stress that I am talking about clear and widely corroborated moral intuitions. Our moral intuitions about our own inherent value are of this sort. I suggest that these intuitions are very stable across time and space, even if moral intuitions about our overall value and the relevance of other factors have not been that stable. If resisting my argument requires challenging the reliability of even our most clear and widely corroborated moral intuitions, then it is a strong argument because resisting it requires embracing a very radical moral skepticism.
Second, it is not obvious to what extent divergent moral intuitions across time and space really do call into question the reliability of moral intuition. For instance, as far as I can tell there is nothing in moral realism per se that commits one to a fixed, uniform moral landscape. Neither the moral supervenience thesis (if two acts have all the same nonmoral properties, they must also have the same moral properties) nor the universalizability thesis (if two acts are similar in all morally relevant respects, they must have the same morality) entail it, for neither says anything about which features of an act are morally relevant, and thus both leave open that an act's temporal and spatial properties could be relevant.
The objectivity of morality does not imply a fixed, uniform landscape either, for the physical landscape is objective yet varies over time and space. So why can't the moral landscape vary as well? Indeed, would not positive evidence that the moral landscape varies over time and space consist in divergent moral intuitions careful, reflective people had over time and space? Divergent moral intuitions may just be indicative of a varying moral landscape. In other words, even if moral intuitions about our inherent value have varied over time (and/or space), this would not necessarily call into question the reliability of those intuitions at any given time and place and thus would not undermine the force of my argument. Our moral intuitions imply that it is necessarily the case that conscious experiences are borne by nonphysical objects and that at this time and place such objects have significant inherent moral value.
It might be objected that there is good reason to discount the evidence of all moral intuitions for the best overall explanation of why the universe appears to us to have a moral dimension is that getting such impressions enabled our ancestors to make more babies and rear them more successfully than those who got no such impressions (see Joyce Reference Joyce2006: 2). By contrast, the best explanation of why we see trees and mountains is that there is an actual physical world out there, and seeing it at least approximately accurately helped our ancestors make babies more successfully than those who could not. In other words, we can explain the existence of moral intuitions without having to posit an actual moral dimension answering to them (and so, on grounds of simplicity, should not posit one). Whereas when it comes to sense impressions, their adaptive value comes from them being at least approximately accurate representations of a real physical world.
Obviously, I cannot consider the credibility of the above case for moral nihilism in any detail. But rejecting my moral argument for substance dualism by embracing moral nihilism is, to say the least, a dramatic way of resisting it. Second, it seems inevitable that any argument for moral nihilism is going to have at least one premise that is prima facie less plausible than the claim that there is something wrong with, say, raping an innocent. Third, it is hard to see how to stop an argument for moral nihilism ending up challenging the reality of the entire normative dimension of the universe. For instance, having true beliefs and adopting methods of belief formation likely to result in these would seem to have considerable adaptive value. But it is the truth of such beliefs—and the tendency of such methods to yield true beliefs—that confers the advantage, not the existence of reasons to believe and adopt those beliefs. It would seem, then, that there do not actually need to be any epistemic reasons in reality in order for the advantage to accrue: it is enough that we get the strong impression that there are and take such impressions seriously. Yet, all intellectual inquiry presupposes that there is a normative dimension to the universe, for epistemic reasons are normative reasons. If this is correct, then any argument for moral nihilism is going ultimately to be ad hoc (singling out morality for debunking but arbitrarily leaving the rest of the normative landscape untouched) or self-stultifying. Obviously, what I have just said above requires more detailed argument than I can provide here, but the more general point I am trying to illustrate is that the plausibility both of moral skepticism and moral nihilism remains very much in question and hardly affords one a reliable base from which to attack a moral argument for substance dualism (or a moral case for anything else, for that matter).
The critic may instead target moral objectivism, arguing that moral claims are not truth-apt. They are not about the world, as such, but are rather expressions of attitude or intent. My reply must be brief, so I will just note that this objection involves adopting a minority metaethical stance, widely recognized to be riven with problems that many of us—myself included—consider insurmountable.
Now for the second objection that despite the strength of any moral case for substance dualism there are overall more powerful reasons to reject substance dualism. Again, considering this objection in detail would require careful scrutiny of all the arguments in question. However, let me just say that I think the case against substance dualism is at present greatly overstated (for some good criticisms of the standard objections to substance dualism, see Rodrigues Reference Rodrigues2014).
Consider one of the most popular ‘problems’ that substance dualism is supposed to face: the problem of interaction. According to this objection, two things of a fundamentally different nature cannot interact. Given that substance dualism has it that the mind is a fundamentally different kind of thing from any physical thing, it follows that minds cannot interact with the physical world. As minds clearly can interact with the physical world, substance dualism must be false. The ultimate bearers of our conscious experiences must be physical.
But ahead of investigation, what possible reason is there to think two radically different sorts of things cannot interact? One might ask ‘how can they?’ But not knowing how something might be the case is not evidence that it is not, or cannot, be the case. I haven't a clue how my computer works. That is not evidence that it isn't working! One might raise the same question about things of the same kind. As Rodrigues puts it:
What is it about immaterial minds that you think makes it harder to enter in causal relationships with physical objects? What is it about causality that makes problematic interaction between different sorts of things? After all, physics gives us numerous examples of very different things interacting with each other: fields and particles, singularities, black holes, forces and charges, etc. (2014: 214)
Ahead of investigation there is no reason to think that radically different sorts of things cannot interact. I have done some investigating above and noticed that moral appearances strongly imply that our minds are not physical things. It also appears that minds can and do interact with the physical. So, upon investigation it appears that radically dissimilar things can and do interact.
Finally, it should be noted that the moral evidence I have presented above is not the only positive evidence for substance dualism there is. There is introspective evidence as well. I suppose I can claim to be an authority on how things appear to me. Personally, I do not just get the impression that there are conscious experiences occurring somewhere inside my head. I get the impression—a mind’s-eye impression—that they are being borne by an object (I call it ‘me’). And this object that appears to be bearing my conscious experiences appears to be inside my head, but positively to be shapeless, sizeless, and colorless. It does not appear to be my brain. Perhaps my brain is, in fact, the ultimate bearer of my conscious experiences. But if that is true, then what appears to me to be bearing my conscious experiences is not bearing them.
Appearances are prima facie evidence for what they represent to be the case, and thus the appearance—the mind's eye impression—that my conscious experiences are being borne by a nonphysical thing that is inside my head is prima facie evidence that they are.
Water is often wheeled in (or poured in) at this point. Water appears to be a colorless, wet liquid, but upon careful investigation it is found to be a collection of tiny molecules. So could not the appearance of the sizeless, colorless, textureless object bearing my conscious experiences turn out to be my brain, just as water turns out to be huge collections of tiny molecules?
The analogy is strained, to say the least. As Huemer puts it:
On the face of it, water doesn't seem to be H2O; but it is not the case that water seems to not be H2O. Our prescientific concept of water takes it to be a clear, odorless, tasteless, etc., liquid. We cannot, on the basis of this concept, discern anything about what its micro-structure might be like. We have no experience of just seeing that there are no tiny particles composing it, and so on. Nor do we have the sense that water is a different category of thing from H2O; on the contrary, we see that they are the same category of thing, namely, physical substances. (2005: 94–95)
Forget tiny molecules for a moment. Could water turn out to be made of practical reasons? No. Indeed, someone who thought it possible that water might turn out to be made of practical reasons is someone we would have to say either had no idea what water is or no idea what practical reasons are (or both). Water has a size, a shape, texture; practical reasons have none of these things. We do not need to know any more about what practical reasons are, in and of themselves, or know more about what water is, in and of itself, to know that water cannot be made of practical reasons (or vice versa). They are just too radically dissimilar. I would say that the same is true of the object that appears to me to be bearing my conscious experiences. It appears positively to be shapeless, colorless, and sizeless. A brain is as radically dissimilar to the thing that appears to be bearing my conscious experiences as practical reasons are radically dissimilar to water. What it would take for the appearance to be accurate is the presence in my head of a shapeless, colorless, sizeless thing. Perhaps there is not one in there, but there would jolly well need to be one if the appearance is to qualify as anything other than an illusion.
Perhaps others do not get the impression of a nonphysical thing bearing their conscious experiences. Hume said he didn’t. He said that ‘when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe anything but the perception’ ([1739/40]Reference Hume and Selby-Bigge1978: 252). But Hume does not speak for everyone. As most introductions to the philosophy of mind are wont to point out: substance dualism is very popular among nonphilosophers (Churchland Reference Churchland1996: 7). Surely, the best explanation of this is not that most people have read and been impressed by the arguments of Descartes or Plato, but that substance dualism describes, at least roughly, how things appear to a great many people?
Also, consider this. As we all know, sensory faculties malfunction from time to time. That is, if there do appear to many of us to be positively shapeless, sizeless, colorless things inside our heads, we would also expect there to be hallucinations of such things, just as there are hallucinatory visual appearances and so on. We would expect there might be ‘sightings’ of positively shapeless, sizeless, colorless things outside of our heads, at least from time to time.
There are such sightings. Lots of them. Appearances of ghosts, spirits, presences, call them what you will, are and have been regularly and consistently reported throughout the history of humankind (they are not culturally specific). In fact, anecdotally many people—perhaps most—have had some sort of experience of a ‘presence’ from time to time. Most of us just do not take them remotely seriously. For instance, I am prey to such appearances when I am very sleep deprived. I have found that after a prolonged period without sleep, I start to get the distinct impression someone has come into the room, despite not seeing or hearing anyone (note, I don't believe there is anyone in the room with me: I believe I am malfunctioning and promptly go to bed!). Here is William Golding describing a character undergoing such an experience in his book The Spire:
And then, quite suddenly, he knew he was not alone. It was not that he saw, or heard a presence. He felt it, like the warmth of a fire at his back, powerful and gentle at the same time; and so immediate was the pressure of that personality, it might have been in his very spine. (1965: 22)
These are not impressions of bundles of free floating conscious experiences. They are appearances of objects, bearers of conscious experiences.
I want to stress that I am not arguing that ghostly presences—disembodied minds—exist. I am arguing that impressions that ghostly presences exist, exist. When we get the impression of such things outside our own heads, we call them presences, spirits, ghosts. Most of us, quite sensibly, consider that such appearances constitute illusions.
Perhaps the appearance of a nonphysical thing inside our own heads constitutes an illusion as well. However, speaking personally, I only start getting the impression of external bodiless presences in extreme circumstances—when I have gone for an unusually long time without sleep—under which I would positively expect to start coming unhooked from reality in some way. By contrast, I get the impression that there is a positively shapeless, sizeless, colorless thing inside my own head all the time. I am getting it right now. There does not seem to be any special reason for me to consider that these appearances constitute illusions. As such, the appearance—occurring under ordinary circumstances—of positively shapeless, sizeless, textureless, colorless objects bearing our conscious experiences inside our heads constitutes prima facie evidence that there are such things inside our heads. Not decisive evidence, of course, but significantly evidence that is corroborated by the moral evidence.
7. Conclusion
My object here has been to draw attention to powerful moral evidence in support of a version of substance dualism about the mind. We have clear, widely corroborated moral intuitions about the value of bearers of conscious experiences: a value that does not derive from the value of the conscious experiences themselves. Among moral realists, moral truths are almost universally held to be necessary truths about our universe. Our moral intuitions provide us with (fallible) insight into what those necessary truths may be. As such, our moral intuitions imply that it is a necessary truth that conscious experiences are borne by a nonphysical thing and that these nonphysical things have significant inherent moral value.
Some hold that moral evidence is not good evidence. But it is hard to make good on that claim. Some may hold that there are good independent reasons for thinking substance dualism is false and that these reasons are powerful enough to overcome any moral evidence there may be. But this is not true, or at least it is highly questionable. Indeed, if anything, there seem to be independent reasons to think substance dualism is true. To many of us substance dualism appears to be true: our conscious experiences appear to us—to our mind's eye—to be being borne by something radically dissimilar to the brain. This is prima facie evidence that they are being borne by something radically dissimilar to the brain, evidence corroborated by the moral evidence I have provided above. If correct, then at least two witnesses whose testimony we have no special reason to distrust, place substance dualism at the crime scene.
