On the Mysteries of Existence

ABSTRACT: Philosophers often argue, "Unless P, X is mysterious; therefore, P" or "The theory that P solves the problem of X; therefore, P." But their arguments are commonly vitiated by the failure to provide any substantive explanation of the alleged problem invoked in the premise. This kind of poor methodology has done untold harm to philosophy. I show this with three well-known examples: Kant's problem of the synthetic a priori, Mackie's "argument from queerness", and the problem of mind/body interaction. I then provide two examples (using the mind/body problem and the problem of memory knowledge) to show what a genuine exposition of a philosophical problem would look like.

There is a well-known story by Douglas Adams in which a race of super-intelligent beings creates a gigantic supercomputer to figure out the answer to the Ultimate Question of life, the universe, and everything.(1) The machine thinks for 7½ million years, and then finally announces that the answer is ... 42. There is a philosophical moral to be found in this story: before you set out in search of answers, make sure you know what the question is. Otherwise, you may be in for a big waste of time. In reality (this is part of the joke), no answer could ever be found to such an undefined question.

The thesis of this essay is one that some will regard as unphilosophical in spirit. It is this: he who claims to apprehend a philosophical problem or mystery has a burden of showing that there is a problem, or of defining a specific question. If this burden is not discharged, as it frequently is not, then the attempt to solve the supposed problem is a waste of time, and the use of the 'mystery' to motivate philosophical positions is misguided. The argument for this thesis is simple: one cannot answer an undefined question, and the difficulty of finding such an answer does not prove anything philosophically interesting. If the mystery monger is unable to show in the first place that there is a problem about X, then one in effect is charged with answering an unspecified question when one undertakes to solve the problem about X, for one hasn't been given a specific problem to solve.

One might anticipate that this lesson would be obvious, particularly to analytic philosophers. But the opposite is the case. Philosophers are largely in the business of finding mysteries to worry about. In analytic philosophy, the goal is usually to trace the mysteries to an opposing philosophical view, announce that one's own view solves them, and thereby demonstrate the truth of one's own view. This creates a nearly unanswerable argument, it being impossible to demonstrate that a proposition is not 'mysterious', when confronted with the vague assertion or implication that it is.

I will give three examples of the argument from mystery below, in which the existence of a philosophical problem is asserted but never demonstrated. It is not my thesis, however, that there are no genuine philosophical problems to worry about. Accordingly, I will give two examples to show how the burden of demonstrating a problem might be discharged. This will help to explain what I mean by demonstrating the existence of a problem and further clarify what is lacking in the first three examples.

I. The problem of a priori knowledge

Immanuel Kant may have been the first to make extensive use of the argument from mystery. It is no exaggeration to say that his entire epistemology rests upon the following argument:


Synthetic, a priori knowledge exists.


Unless my (Kant's) theory is true, its existence would be mysterious.


Therefore, my theory is true.

In the introduction to the Critique, after arguing for the existence of synthetic, a priori knowledge, he immediately (without further motivation) proceeds to the question, 'How is synthetic, a priori knowledge possible?'(2) His theory is supposed to provide the only available answer to that question -- which is just another way of stating (2). Yet, despite the importance Kant attributes to this 'problem of pure reason', he has almost nothing to say about what exactly the problem is.

The question, 'How is synthetic, a priori knowledge possible?' presupposes that there is something problematic about synthetic, a priori knowledge -- it presupposes, in other words, that there is some reason for thinking that synthetic, a priori knowledge would not be possible. One can see this by reflecting on appropriate and inappropriate uses of the 'How is X possible?' form of question.

Suppose that, as I am checking out a book at the library, the librarian informs me that I have an overdue book. I reply, 'How is that possible?' The librarian would probably be puzzled, and have no idea how to answer my question. Notice that the question is not, 'How does one get overdue books?' That question would be odd only in the sense that it would be odd that a person of my age and education should need to ask it. But the question, 'How is it possible that I have an overdue book?' would be odd in the sense that it doesn't really make sense in the context. The latter question presupposes a reason for thinking that I could not have an overdue book, as the former does not.

Now imagine a different scenario. The librarian informs me that I have an overdue book. This time, I say, 'This is the first time I have used this library. How is it possible that I have an overdue book?' Now my question becomes appropriate. The difference: in this scenario, I have supplied the reason for thinking that I could not have an overdue book, before asking the 'how possible' question.

Sometimes, of course, it is not necessary to explicitly state the reason for thinking that something is impossible. Suppose that a detective is called to work on a murder case. The body was found outdoors, but there are no footprints leading to or away from the scene of the crime. Upon being apprised of this fact, the detective says, 'But how is that possible?' He does not find it necessary to supply a reason for believing the absence of footprints to be impossible. But this is only because the facts that comprise that reason would already be obvious to all: some person transported the victim (whether before or after killing him) to the location where he was found. People generally travel along the ground. When they do so outdoors, they generally leave footprints in the ground. Footprints can generally be detected. Hence, how is it possible that no footprints were found? As this example shows, one need not have a conclusive reason for thinking X to be impossible before asking, 'How is X possible?' becomes appropriate (on the contrary, the question 'How is X possible?' presupposes that X is possible). What one needs is a prima facie reason for thinking X to be impossible.

Kant, then, was under an obligation to demonstrate the existence of a problem of synthetic, a priori knowledge, in the sense of providing some prima facie reason for denying its possibility (assuming, as is the case, that this reason is not already obvious to all). No such reason appears when the alleged problem is first posed in the introduction. One hopes that it will be supplied later on, when he gets down to the real business of elaborating his theory. Again, no. After arguing that there is synthetic, a priori knowledge of space (geometry), Kant attempts to justify his own theory of the nature of space as the 'form of outer intuition', with the following remarks:

How, then, can there exist in the mind an outer intuition which precedes the objects themselves, and in which the concept of these objects can be determined a priori? Manifestly, not otherwise than in so far as the intuition has its seat in the subject only, as the formal character of the subject, in virtue of which, in being affected by objects, it obtains immediate representation, that is, intuition, of them; and only in so far, therefore, as it is merely the form of outer sense in general.
     Our explanation is thus the only explanation that makes intelligible the possibility of geometry, as a body of a priori synthetic knowledge.(3)

If Kant has a valid argument here, it is this:


Synthetic, a priori knowledge exists.


Unless my (Kant's) theory is true, synthetic, a priori knowledge is impossible.


Therefore, my theory is true.

Kant spends plenty of time arguing for premise (1). Yet, incredibly, he has no argument for premise (2). The word 'then' in the first sentence of the above quotation suggests that Kant has just said something to motivate the question which that sentence poses. But in fact, all that precedes it is Kant's argument to show that geometry is really a priori. No explanation of what is problematic about that appears. All we are told is that it is 'manifest' that synthetic, a priori knowledge of space (N.B., 'precedes' in the quotation presumably is not to be read temporally but somehow epistemologically) could not exist unless space were a form of intuition. What I have quoted above is the whole argument. This, then, is a paradigm case of an illegitimate argument from mystery.

II. The argument from queerness

Our second example of mystery mongering is J.L. Mackie's 'argument from queerness'. Mackie argues that objective moral properties cannot exist, because if they did, 'then they would be entities or qualities or relations of a very strange sort.'(4)

Fortunately, Mackie has more to say. He lists three specific features of objective values that make them 'queer'. First, he says that our knowledge of such values could not be accounted for by 'sensory perception or introspection or the framing and confirming of explanatory hypotheses or inference or logical construction or conceptual analysis, or any combination of these.'(5) He asserts, but admits he has not argued, that all other, legitimate knowledge can be accounted for by these sources (and if some other alleged items of knowledge cannot be so accounted for, then they too are to be counted targets of the argument from queerness). He concludes that the moral realist must appeal to intuition.

Mackie's assumption that the list of forms of cognition he provides is complete as far as non-ethical knowledge goes, can certainly be questioned. But let us grant him that assumption. Let us grant him, too, that the objectivist must use moral intuition to explain our knowledge of objective values. Given that, has Mackie shown something queer or mysterious about objectivism?

No. There is no argument against intuitionism here. There is an implication that intuitive knowledge is mysterious or problematic, but no hint as to why this might be. Mackie makes exactly two remarks about what is wrong with intuitionism.(6) First:

Intuitionism has long been out of favour, and it is indeed easy to point out its implausibilities.(7)

One anticipates that this sentence is to be followed by a demonstration of the ease with which this may be done. Instead, Mackie proceeds to argue that all forms of objectivism are committed to an appeal to intuition, the 'implausibility' of such an appeal being assumed as obvious. Second:

'[A] special sort of intuition' is a lame answer, but it is the one to which the clear-headed objectivist is compelled to resort.(8)

Again, one hopes in vain for some expansion on the nature of this lameness.

Mackie's second example of the queerness of objective values concerns their intrinsic action-guiding power. According to Mackie, if there are objective values, then when a person becomes aware of them, that person necessarily has a motive to act in a certain way (e.g., to promote that which is objectively good), no matter what contingent psychological traits he might have. A right action would have 'to-be-pursuedness somehow built into it.'(9) The term 'somehow' clearly signals the mysteriousness of this property.

Mackie's interpretation of the idea of objective values is questionable.(10) But let us, again, grant him this assumption for purposes of investigating the charge of mystery mongering. If Mackie is correct that objective values, by definition, have this kind of action-guiding character and that nothing else does, has he thereby demonstrated a problem about objective values?

No. No argument is given against the existence of such action-guiding entities. The closest Mackie comes is this:

The need for an argument of this sort [i.e., the argument from queerness] can be brought out by reflection on Hume's argument that 'reason' -- in which at this stage he includes all sorts of knowing as well as reasoning -- can never be an 'influencing motive of the will'. Someone might object that Hume has argued unfairly from the lack of influencing power (not contingent upon desires) in ordinary objects of knowledge and ordinary reasoning, and might maintain that values differ from natural objects precisely in their power, when known, automatically to influence the will. To this Hume could, and would need to, reply that this objection involves the postulating of value-entities or value-features of quite a different order from anything else with which we are acquainted, and of a corresponding faculty with which to detect them.(11)

Assuming, as Mackie does, that (at least part of) the thesis of objectivism is that there are things, called 'values', such that awareness of them necessarily constitutes or creates a motive for action, certainly neither Mackie nor Hume could, without begging the question, take it as a premise that there are no such things. Yet that appears to be the import of the first sentence in the above quotation. No argument is brought forth to show that reason (or rather, as Mackie explains Hume really meant, knowledge) cannot be a source of motivation, and the objection Mackie considers in the second sentence, by Mackie's own lights, just restates the thesis that Hume is supposed to be arguing against. The last sentence comes closest to presenting an argument for the Humean thesis that Mackie endorses. Yet the argument, if that is what it is, amounts to no more than this: Nothing other than objective values is intrinsically action-guiding; therefore, objective values do not exist. Surely this is enthymematic. Asked to supply the suppressed premise, a logic student might reply: 'There does not exist a class of entities, X, and a property, P, such that all and only the members of X have P.' To put that another way: Mackie is arguing that objective values are queer; therefore, they don't exist. What makes something 'queer', apparently, is that it possesses properties that no other type of thing has. Thus, it seems Mackie's argument requires the assumption that there is no kind of thing having properties that other kinds of things lack.

But I doubt Mackie believed that general claim.(12) In any case, he certainly does not argue for it. He does not explain why, assuming that values have properties which other kinds of things lack, this situation should be regarded as mysterious or problematic. Rather, it appears that he just found this particular property, the intrinsic prescriptivity of values, to be weird.

Lastly, Mackie adverts to the supervenience of moral properties on non-moral properties. He says that this relation is not one of logical or semantic entailment but that nevertheless, moral properties in some sense are supposed to depend on non-moral properties. He continues:

Something must be postulated which can see at once the natural features that constitute the cruelty, and the wrongness, and the mysterious consequential link between the two. Alternatively, the intuition required might be the perception that wrongness is a higher order property belonging to certain natural properties; but what is this belonging of properties to other properties, and how can we discern it?(13)

Leaving aside the epistemological objection, what does Mackie's argument amount to? The supervenience of moral properties is mysterious; or the phenomenon of a property belonging to another property is mysterious. Why is the supervenience of moral properties mysterious? Well, it's not logical or semantic entailment, but it is not merely co-instantiation of properties either. This is all that Mackie has to say concerning the nature of the mystery. He has even less to say -- nothing, in fact -- concerning the mysteriousness of second-order properties. The second quoted sentence above implies that second-order properties are mysterious, but it neither asserts nor argues for this.

And this points up an important feature typical of uses of the argument from mystery. Mackie here uses a question, rather than making a statement, in the course of his argument. This has the rhetorical effect of apparently shifting the burden of proof from oneself onto one's opponent. It now seems to be the burden of the opponent to answer your question -- and in this case to prove that a property's belonging to another property is not mysterious. Mackie, seemingly, has no burden to prove anything, since he did not actually assert anything. He didn't actually say that second-order properties were mysterious -- he merely implied it. (Recall Kant's similar use of the question, 'How is synthetic, a priori knowledge possible?')

But this is illegitimate. Mackie is making a claim: all values are subjective. He is ostensibly presenting an argument for that claim. A question is not a premise or any other part of an argument, though rhetorical questions can of course have expository value. Therefore, if Mackie's question, 'What is this belonging of properties to other properties?' has any legitimate role in his argument, it should be possible to paraphrase it away -- that is, to make Mackie's point using only statements. In fact, the attempt to do so destroys the rhetorical force of the passage, making its mystery mongering character apparent: 'Alternatively, the intuition required might be the perception that wrongness is a higher order property belonging to certain natural properties; but the belonging of properties to other properties is mysterious.' Or, still more explicitly: 'Alternatively, the intuition required might be the perception that wrongness is a higher order property belonging to certain natural properties; but that can't be.' Once Mackie's point is phrased in this way, it becomes easy to see the criticism that Mackie has not in fact demonstrated any problem about second-order properties.(14)

III. The mind/body problem

We turn at last to the greatest alleged mystery of all. All philosophers know that the coexistence of mental and physical things is tremendously mysterious (at least, if dualism is true). Philosophers as diverse as Dennett and Searle can agree on this. Thus, Dennett:

What could be more obvious or certain to each of us than that he or she is a conscious subject of experience, an enjoyer of perceptions and sensations, a sufferer of pain, an entertainer of ideas, and a conscious deliberator? That seems undeniable, but what in the world can consciousness itself be? How can living physical bodies in the physical world produce such phenomena? That is the mystery.(15)

What is the mystery? No motivation is given for the questions in the above passage, and no mysterious feature of consciousness is pointed out. Again, we see the use of questions to make undefended implications. It is implied that we have no idea 'what consciousness is', and it is implied that the production of consciousness by physical phenomena is mysterious, but no reason is given for either of these propositions. And here we must recall the lesson we learned from Kant: the question, 'How is X possible?' or 'How can that be?' presupposes a prima facie reason for holding X to be impossible.

The emptiness of the above explanation of the mystery of consciousness can be demonstrated by substituting something else for 'consciousness' -- that is, substituting something that one is not antecedently convinced is mysterious. Suppose I wanted to convince you that there is a great philosophical mystery about sticks. Asked to explain the problem, I reply:

What could be more obvious to us than that there are sticks, little ones and big ones, on the ground and on trees? That seems undeniable, but what in the world can sticks themselves be? How can trees produce such phenomena? That is the mystery.

I trust no reader will say that I have just demonstrated a problem of sticks. But I have said as much to define my problem as Dennett has to define his.

To take a more philosophical example, I might, if the procedure we have so far seen employed by Kant, Mackie, and Dennett is legitimate, evince a philosophical mystery of existence in the following manner: What could existence be? And how can things exist? If that is to be accepted as defining a philosophical problem, then I am certain that we will find this problem every bit as difficult to solve as the three philosophical problems so far discussed.

It appears that John Searle is even more philosophical than Dennett, because Searle locates no less than four distinct mind/body problems.(16) He calls them, respectively, the problem of consciousness, the problem of intentionality, the problem of subjectivity, and the problem of mental causation. Here is a sample:

We all suppose, as part of common sense, that our thoughts and feelings make a real difference to the way we behave, that they actually have some causal effect on the physical world. I decide, for example, to raise my arm and -- lo and behold -- my arm goes up. But if our thoughts and feelings are truly mental, how can they affect anything physical? How could something mental make a physical difference? Are we supposed to think that our thoughts and feelings can somehow produce chemical effects on our brains and the rest of our nervous system? How could such a thing occur? Are we supposed to think that thoughts can wrap themselves around the axons or shake the dendrites or sneak inside the cell wall and attack the cell nucleus?(17)

This is the entire exposition of why mental causation is problematic. It consists of little more than a series of questions of the form, 'But how can that be?' No prima facie reason for doubting the possibility of mental causation is brought forward. The last sentence contains three examples of ways in which mental events presumably do not act on the physical world, but no suggestion is made that this is an exhaustive list of the possibilities, so there is no argument against the possibility of mental causation to be found here.

Let me make clear what I am and am not using these examples for. I am not claiming that no philosopher has said anything worthwhile towards defining the mind/body problem. Some may well have done better than Dennett and Searle. Rather, I am using the examples to draw attention to a point about philosophical method. These are examples of bad philosophical method -- this sort of thing is to be avoided. Dennett and Searle ask us to ponder a philosophical problem, and later to evaluate their solutions, while the problem itself is never clearly defined.

But some will say at this point that I have been unfair to Dennett, because Dennett does have more to say later on about the mystery of consciousness than what I have so far quoted. Or rather, he has something to say about why dualism is mysterious. Dennett makes it explicit that his reason for avoiding dualism 'at all costs' is that, if dualism is true, then consciousness is 'mysterious' and impossible to understand scientifically(18) -- a classic argument from mystery. Why does he think dualism entails mystery? At one point, he sounds as though he wants, uninterestingly, to stipulatively define dualism as the view which makes consciousness mysterious.(19) But there is one substantive argument. It is based on the problem of mental causation. In the interests of fairness, then, let us examine this argument:

[Responding to Descartes.] How, precisely, does the information get transmitted from pineal gland to mind? Since we don't have the faintest idea (yet) what properties mind stuff has, we can't even guess (yet) how it might be affected by physical processes emanating somehow from the brain, so let's ignore those upbound signals for the time being, and concentrate on the return signals, the directives from mind to brain.(20)

We have to pause here. On the Cartesian dualist view that Dennett is considering, 'mind stuff' just means 'the mind'. So what Dennett has just asserted is that, if Cartesian dualism is true, then we haven't the faintest idea what properties the mind has. This, if true, would certainly be enough to establish that dualism renders the mind mysterious. Indeed, since the transparency of mental phenomena is one of the better-known elements of Cartesian philosophy, if Dennett could support his claim, he would have the strongest possible grounds for rejecting Descartes' view of the mind: namely, that it is self-contradictory. Unfortunately, Dennett gives us no hint as to how he arrived at that startling claim.

Let us, then, proceed to see why he believes that the mind could not affect the brain (picking up where we left off):

These, ex hypothesi, are not physical; they are not light waves or sound waves or cosmic rays or streams of subatomic particles. No physical energy or mass is associated with them. How, then, do they get to make a difference to what happens in the brain cells they must affect, if the mind is to have any influence over the body?(21)

So far, Dennett is doing no better than Searle. There is no content to the above passage other than the now-familiar, unmotivated 'But how can that be?' question. But now at last we come to something more substantive:

A fundamental principle of physics is that any change in the trajectory of any physical entity is an acceleration requiring the expenditure of energy, and where is this energy to come from? It is this principle of the conservation of energy that accounts for the physical impossibility of 'perpetual motion machines,' and the same principle is apparently violated by dualism.(22)

Here at last is a genuine problem with dualism, if Dennett is right: it contradicts a well-confirmed law of nature. Violations of energy conservation are known in quantum mechanics, but let us stick to the classical physics that Dennett seems to be appealing to. Since 'acceleration' is synonymous with 'change in trajectory', the principle Dennett states in the first sentence says that any acceleration requires the expenditure of energy. The principle of the conservation of energy, on the other hand, says that the total quantity of energy is neither increased nor decreased in any process.(23) I do not see how Dennett's statement can be interpreted as equivalent to the latter; indeed, it is not so easy to see how Dennett's statement is to be interpreted as being consistent with the conservation of energy. In light of the idea that energy is never created or destroyed, it is unclear what Dennett means by its 'expenditure'.

Charitable readers will suggest that by 'the expenditure of energy', Dennett meant 'the transfer or changing of form of energy'. Even so, Dennett's principle is not a statement of the conservation of energy, nor is it true. (Consider the case of a body in a fixed, circular orbit around the earth. The curvature of its path constitutes a constant acceleration, but there is no change in either the body's kinetic energy or its gravitational potential energy over time.)

But confusion over the laws of physics is not my target here. I am claiming that Dennett has made an error of philosophical method, not merely an error of physics. Therefore, let us suppose that Dennett's principle of the expenditure of energy were true. Then would Dennett have located something mysterious about mental causation?

Still, no. Dennett's refutation of interactionism requires at least three premises:


All (relevant?) physical changes consist in accelerations.


All acclerations require energy to be transferred or to change form.


Mental phenomena could not cause energy to be transferred nor to change form.

This is what he needs in order to show that mental phenomena cannot cause any physical changes. Even if we (incorrectly) grant Dennett that (1) and (2) are true, he has yet presented no argument whatever for the crucial premise (3), as can be verified by inspection of the above quotation. Thus, he has asserted but not demonstrated the existence of a problem of mental causation.

We are not through yet. Setting aside his appeal to the conservation of energy, Dennett next compares the alleged incoherence of dualist interactionism with an incoherence in stories about Casper the Friendly Ghost:

How can Casper both glide through walls and grab a falling towel? How can mind stuff both elude all physical measurement and control the body? A ghost in the machine is of no help in our theories unless it is a ghost that can move things around -- like a noisy poltergeist who can tip over a lamp or slam a door -- but anything that can move a physical thing is itself a physical thing (although perhaps a strange and heretofore unstudied kind of physical thing).(24)

But here Dennett reverts to the simple question-begging approach we have complained of all along. No reason is brought forward to show that the mind could not simultaneously elude measurement and control the body -- unless, of course, one counts any observation of the effects of something as 'measuring' it, in which case the interactionist dualist will insist that the mind can be 'measured'. Provided that not all effects of X are such that observing them counts as measuring X, I see no reason why it could not be true that mental phenomena have observable, physical effects but cannot be measured (not that this is essential to dualism). Nor is any reason here brought forward as to why anything that can move a physical thing must itself be physical. I conclude that Dennett's problem of mental causation is empty.

Surely I am not claiming, am I, that there is no point to asking how the mind affects the brain? That this is entirely obvious, or anyway it needs to be proven that it is not obvious? No, that is not what I am claiming. There is indeed a good question along those general lines. There is at the least this question: assuming that the mind affects the body, and assuming that all instances of causation can be subsumed under laws, what are the laws of mental causation? This is a good scientific question. But this is not a philosophical mystery, any more than the question 'What are the laws of electromagnetism?' is or ever was a philosophical mystery. The philosophical question which Dennett and Searle are posing is: How is it even possible that the mind affects the body? This is the question about which I am complaining that it needs motivation, and has received none from these authors.

IV. The mind/body problem revisited

We have so far seen several examples of culpable failure to define philosophical problems. Assuming that we could find a genuine philosophical problem, what would a non-question-begging, substantive exposition of the problem look like? Here is one example.

There is a problem about the relation between the mind and the body. Consider the following five theses:


Given any composite system, the properties of the whole are a necessary consequence of the properties, activities, and arrangement of the components.

This is an intuitively plausible principle, and it seems to follow from the general idea that the whole is nothing over and above the collection of parts, suitably arranged. In a full discussion of the mind/body problem, one would bolster its plausibility through several illustrations -- e.g., how the solidity of a table is explained through the arrangement of and interaction between the molecules composing it;(25) how the color of a surface (understood as spectral reflectance, of course, not disposition to cause sensations with certain qualia) can be explained by the behavior of the molecules in it; how the capacity of living things to grow and reproduce is explained by the activities of the cells that compose them. The modality in (1) is metaphysical, so these explanations would involve appeal only to the properties, activities, and arrangement of components, and not to any other contingent principles. And of course, it must be specified that 'properties' is not to be interpreted in a trivializing sense, whereby 'being such that, if made part of such-and-such composite system, the system has property P' would count as a property of one of the components. With these provisos, I do not believe there are any known exceptions to (1), aside from the case of consciousness and certain cases in quantum mechanics.(26)


People are made of atoms.

This proposition, too, is quite plausible. It could be bolstered by considering examples of how one determines what a thing is made of. When human beings are examined, dissected, and the like, nothing but tissues composed of cells composed of atoms is found. We can see and touch people, weigh them, and the like, just as we do to other physical objects (this is how we each know that there are other people). All the other such physical objects in the world are known to be composed of atoms, and the same sort of experiments can be used to determine the chemical composition of a person.


Atoms are purely physical things: their properties are all physical properties, their activities are physical events, and their relations to each other are physical relations.

I take it that this doesn't need much discussion. Atoms, for example, are not conscious.


People have mental states.

We believe things, feel things, want things, and so on. We have pains, itches, and, once in a while, pleasures.


The existence of a given mental state is not a necessary consequence of the existence of any purely physical state.

Again, the modality is metaphysical. This is where one brings in such things as Jackson's thought experiment about Mary,(27) the inverted color spectrum, and zombies. (One only needs one example of (5) to make out the problem.)

Now, the problem is: statements 1-5 are jointly incompatible. I think this is a real and difficult problem, because I feel the pull of each of these 5 propositions. I don't know the answer to it. Nevertheless -- and here is the point -- given how I have defined the problem, at least we know what we're looking for. We know what is supposed to be puzzling and what one is supposed to do to solve the problem. A would-be solver of the mind/body problem has to determine which of these 5 propositions is false, convince us that his choice is the right one, and refute the considerations that support that proposition. Notice how utterly different this is from the alleged problems identified by Kant, Mackie, Dennett, and Searle. Here, I have not merely said, 'But how can that be?' Rather, I have pointed out the specific claims that lead to a contradiction.

V. The problem of memory knowledge

Let's look at another kind of problem. There is a problem about how factual memory provides us with knowledge. By 'factual memory', I mean what happens when a person recalls that P. For example, I now recall that the earth is about 93 million miles away from the sun. I learned that once. I don't remember when or how I learned it, but I know that it's correct.

Knowledge is a form of justified belief, so the question of what kind of justification we have for memory beliefs naturally arises.(28) Why am I justified in thinking that the earth is 93 million miles from the sun? 'Because I remember it' is the first answer that springs to mind, and no doubt correct. But this isn't the sort of answer I'm looking for, so I will give some examples of the sort of answer I'm looking for.

First, perhaps my justification is inferential. And perhaps it is something like this: I now seem to remember that the earth is 93 million miles away from the sun. In the past, I have generally found that expectations formed on the basis of my seeming memories have been borne out. For example, I seemed to remember my address; and when I went to that address, I found an apartment of just the sort I was expecting. This strongly confirms that my seeming memories are highly reliable. Therefore (probably), it is true that the sun is 93 million miles away from the earth.

The most obvious problem here is one of circularity, for I have used claims about the past, based on memory, in my argument for the reliability of memory.

Perhaps, then, my justification is non-inferential. Perhaps memory experiences create the same sort of foundational justification that (some epistemologists argue) sensory experiences do. Just having a sensory experience that P makes one prima facie justified in believing P, and similarly, having an experience of seemingly remembering that P makes one prima facie justified in believing that P.(29)

This view has counter-intuitive results. Suppose I initially learn that P by means of an a priori proof of it (the proof is short, so I can hold it all in mind at once and do not need to use memory). So I have an adequate justification for believing P from the start. However, a few moments pass, and I now am able, in addition, to recall that P. If I entertain the proof while also remembering that P, I will now have two justifications for P, one inferential and one foundational. It seems that my warrant has become more secure with the passage of time. The possibility of mistakes (even in short proofs) makes my warrant less than completely conclusive, but by employing memory, I have increased it. That seems wrong.

Here's a different case. Suppose that I initially adopt the unjustified belief that P (perhaps by wishful thinking or some such irrational process). The next day, however, my belief is adequately justified, because I now seem to remember that P. The passage of time has transformed my irrational belief into a rational one.

It might be thought that in this latter case, I have a defeater for P, since I can recall that I adopted P by wishful thinking. Therefore, modify the case as follows: a number of years pass, and I no longer recall how I initially 'learned' that P, but I still clearly 'remember' that P.(30) For example, suppose that I initially accepted the existence of life after death by wishful thinking. I now no longer remember where I got that belief, but I just seem to remember that that's something I know. On the other hand, my brother Pete adopted the same belief in exactly the same way. However, his memory is better than mine, so he also remembers how he got the belief. As a result, my belief system is rational and his is not. That seems wrong.

Here is a third view. When I remember that P, my justification for believing P is whatever it was to begin with. Memory just preserves the justification (or lack of it) of my beliefs.(31) So my justification for thinking that the sun is about 93 million miles away is that Mrs. Kim in second grade told me that it was -- even if I don't know that that is my justification. This seems more natural than the preceding two theories.

But now recall Russell's five-minute hypothesis. Suppose God created someone five minutes ago in exactly the state that I was in five minutes ago, surrounded by exactly the same kinds of things. Call this person Mike2. Mike2 was created complete with false memories of his past life, identical to my memories of my past life. He thinks his name is 'Mike' and is presently writing a paragraph about the problem of memory knowledge. His situation would be (to him) indistinguishable from my actual situation. Usually, this scenario is mentioned for the purpose of asking, How do I know I'm not actually in that situation? But here I mention it to make a positive point. What sort of things would it be rational for Mike2 to believe? Pretty clearly, just the same things that it is rational for me, now, to believe (modulo appropriate changes in indexical references). Most of Mike2's beliefs about his own past are false, but he has no way of knowing that, and no more reason for suspecting it than I have for suspecting that my beliefs about my past are false. So if I am justified in believing that I ate a bagel this morning, Mike2 is justified (though mistaken) in believing that he ate a bagel this morning. Furthermore, it seems that he has the same degree and kind of justification that I now have.

But of course, this contradicts the above theory of memory knowledge. According to that view, memory merely preserves one's initial justification for a belief. Therefore, I am adequately justified in believing that I ate a bagel this morning, on the basis of sensory evidence. Mike2 has no such justification, since he never had any sensory experience of eating a bagel. At minimum, he does not have the same sort of justification that I have, and it appears that he has no justification at all. On this theory, then, Mike2 is highly irrational (unlike myself), even though he is intrinsically identical with me.

Thus, there is an interesting problem of how memory beliefs are justified. I don't claim that the above three theories are the only alternatives. But they are the three alternatives that occur most naturally (to me, at least). My exposition of this philosophical problem, then, does not consist in a proof of the impossibility of memory knowledge, and it doesn't even (as in the previous case) involve a logical contradiction among enumerated propositions. Still, I have said something substantive -- I have indicated in a non-question-begging way why the most obvious alternatives seem to me unacceptable -- and -- this is the important part -- I have in the process made it clear what sort of thing I am looking for. I am looking for a theory like the three mentioned above, but not subject to the same sort of objections. This theory would say whether memory knowledge is foundational or inferential (or, as in the last theory, if it differs for different cases). If inferential, it would describe the premises and form of inference involved. If foundational, it would state the condition under which foundational justification appears (e.g., the occurence of a seeming-memory experience). By way of explaining what the problem is, I have offered much more than a mere, 'How can memory provide us with knowledge?' As a result, my question is determinate and answerable.

VI. Lessons of philosophical method

I am confident that my use of the examples in the first three sections will be misinterpreted by some. If you are inclined now to ask me for my theory of mental causation, or my argument for the existence of a priori knowledge, then you have misinterpreted it. I have not here asserted the existence of a priori knowledge, objective values, or mental causation. That is not what this paper is about.

This paper is about philosophical method. The philosophers of sections I-III have used poor philosophical method. Each of them has taken some phenomenon to be mysterious or problematic, but none of them has presented any substantive reasons for their assumption. This is especially egregious because (with the possible exception of Searle) they have each used the assumption to motivate an important philosophical conclusion. Kant uses the mystery of a priori knowledge to motivate transcendental idealism. Mackie uses the mysteries of moral value to motivate moral skepticism. And Dennett uses the mystery of mental causation to motivate physicalism. If the 'mysteriousness' of a phenomenon is going to be used as a premise in a central philosophical argument, then that premise certainly needs to be defended. In most cases, key premises of key arguments are carefully examined and defended in analytic philosophy, with this important exception: when the premise is that there exists a certain philosophical 'mystery' or 'problem', the premise is almost never scrutinized.

In response to my complaint, one might at first wonder how I propose that one go about arguing for the existence of a mystery, or whether it is even possible to do such a thing. I think it is possible, the impossibility being to argue positively against the existence of a mystery whose nature has never been articulated. Accordingly, I have used the examples of sections IV-V to show how one can demonstrate a philosophical problem. Some readers may have answers to the problems I posed in those sections. That's fine. The idea of a 'philosophical problem' is not to be understood in such a way that there can never be a genuine solution to one (I don't think there are any problems of that sort). Rather, what I have done is to demonstrate prima facie problems, which someone might well have answers for. In contrast, the authors discussed in I-III have not even demonstrated prima facie problems.

In brief, the point of philosophical method is this. 'How can that be?', by itself, is not an explanation of a philosophical problem. Nor is 'that's mysterious' or 'that's weird' a substantive objection to a philosophical position. Yet, incredibly, there are several important philosophical positions to which the leading objection or one of the leading objections in contemporary philosophy is of this kind. A simple, 'But that just can't be' response would have the advantage of conveying the same content with more directness.

It is not easy to calculate the harm that the argument from mystery has done to contemporary philosophy. I have intentionally chosen two of the best-known contemporary philosophers of mind, one of the best-known contemporary moral philosophers, and one of the greatest philosophers of the Enlightenment, as case studies. Nor could the arguments I have chosen be described as uninfluential, or their topics unimportant. And nor, finally, are these the only similar examples I could have chosen.(32)

I am not one who believes that all premises need to be argued for. I am a foundationalist. Moreover, I concede that a premise which is sufficiently obvious already does not need to be argued for (regardless of whether it is truly foundational or not). If this were not so, no finite philosophical paper or book could be written without offending philosophical method. I also concede that sometimes the problematic nature of a proposition is sufficiently obvious to need no explanation. For example, I think the problematic nature of the conjoint proposition that God is loving and benevolent and will condemn most human beings to eternal suffering is sufficiently obvious that no lengthy explanation of the problem is required. This is to say that the prima facie impossibility of that proposition is sufficiently obvious that no argument is needed. It is not to say that I would be unwilling to listen to attempts to resolve the apparent contradiction.

So the propriety of the above philosophers' methods is partly a matter of judgement: if it is already self-evident, for example, that there cannot be intrinsically prescriptive entities, then my criticism of Mackie fails. If it is already sufficiently obvious that mental causation is impossible that it requires no explanation, then my complaint against Dennett and Searle evaporates. I can only report, therefore, that for my part, I do not find that it is.


1. Douglas Adams, The Hitchhiker's Guide to the Galaxy (New York: Harmony Books, 1980).

2. Critique of Pure Reason, tr. Norman Kemp Smith (New York: St. Martin's Press, 1965).

3. Critique, B41 (emphasis in original).

4. J.L. Mackie, Ethics: Inventing Right and Wrong (New York: Penguin Books, 1977), p. 38.

5. Ethics, p. 39.

6. Excluding his earlier 'argument from relativity', which is supposed to be a separate argument.

7. Ethics, p. 38.

8. Ethics, p. 39.

9. Ethics, p. 40.

10. See William Frankena's excellent discussion, 'Obligation and Motivation in Recent Moral Philosophy' in Essays in Moral Philosophy, ed. A.I. Melden (Seattle: University of Washington Press, 1958), pp. 40-81.

11. Ethics, p. 40.

12. The claim implies that there are no properties, since otherwise the class of objects having P would always be a counter-example.

13. Ethics, p. 41.

14. Grant Sterling gives some responses to Mackie similar to my own in his excellent Ethical Intuitionism and its Critics (New York: Peter Lang, 1994), chapter 3.

15. Daniel Dennett, Consciousness Explained (Boston: Little, Brown & Co., 1991), p. 25.

16. But Searle is far from the record holder; Michael Tye (Ten Problems of Consciousness (Cambridge, Mass.: MIT Press, 1995)) counts ten problems, and there may be others who have found more.

17. Minds, Brains, and Science (Cambridge: Harvard University Press, 1984), p. 17.

18. Consciousness Explained, p. 37.

19. Consciousness Explained, p. 37.

20. Consciousness Explained, p. 34.

21. Consciousness Explained, pp. 34-5.

22. Consciousness Explained, p. 35. In fact, the impossibility of perpetual motion machines is due to the second law of thermodynamics. See Douglas C. Giancoli, Physics for Scientists and Engineers (Englewood Cliffs, N.J.: Prentice Hall, 1989), chapter 22.

23. See Giancoli, Physics, p. 167.

24. Consciousness Explained, p. 35 (emphasis in original).

25. Contrary to philosophical opinion, solidity is far from being an emergent property. Defining properties of solids include having a fixed size and shape (as opposed to liquids, which conform to the bottom of the container they are placed in, and gases, which expand to fill the container they are put in) and having a certain amount of resistance to sheer, tension, and compression forces. These properties strongly supervene on dispositions of the body to deform or not deform in certain ways, which strongly supervene on dispositions of the component molecules to move in certain ways under certain conditions.

26. I refer here to 'entangled' states of two-or-more-particle systems, in which the state of the system doesn't supervene on any collection of states of individual particles (perhaps more accurately: in which there isn't any such thing as the state of a component particle considered individually).

27. Frank Jackson, 'Epiphenomenal Qualia', Philosophical Quarterly 32 (1982): 127-36.

28. According to internalists. But even if 'knowledge' does not mean something along the lines of 'justified, true, belief ...', the question still arises naturally, since we all treat our memory beliefs, and other beliefs based on them, as perfectly justified.

29. John Pollock's view (Contemporary Theories of Knowledge (Totowa, N.J.: Rowman & Littlefield, 1986), pp. 50-2).

30. David Annis uses this kind of case to refute Pollock's view ('Memory and Justification', Philosophy and Phenomenological Research 40 (1980): 324-33, pp. 325-6).

31. This is Norman Malcolm's view, Knowledge and Certainty (Englewood Cliffs, N.J.: Prentice-Hall, 1963), pp. 229-30. This is also the view Annis is defending in 'Memory and Justification'.

32. Consider the mysteriousness of the correspondence theory of truth, the mysteriousness of necessary connections detected by Hume, the 'magical' theory of reference that Hilary Putnam criticizes (Reason, Truth and History (Cambridge: Cambridge University Press, 1981), chapter 1), and the mysteriousness of foundational knowledge. Each of these warrants investigation.