“Skepticism relieved two terrible diseases that
afflicted mankind: anxiety and dogmatism.”
— Sextus Empiricus (c. 200 CE)
Patient: Help me, doctor! I know too much!
Doctor: Goodness me, what a curious complaint! But don’t worry. We’ll get it sorted out. Here, have a half-full glass of water, or what at least has all the properties of normal water. I have put a straw in it. Isn’t it curious how it appears to be broken at the water line?
Patient: (slurps) Ah, thank you.
Doctor: Now why is it you think you know too much?
Patient: I’m afraid I shall have to be immodest, if you are to understand my problem. I am insatiably curious and am always reading about science, history, politics, economics, literature, philosophy, and, well, everything. I have a fantastic mind: I understand things very quickly and make astute connections among the things I learn. And I rarely forget anything I have read.
Patient: And if I am honest, I must say I have the most logical mind I’ve ever encountered. I draw inferences like nobody’s business! I have been busy over the last few years writing a long book which I am titling The Encyclopedia of All Human Knowledge. And, well, not to brag, but just to tell you how things are, I am certainly the person to write it, for there are very few things that belong in an encyclopedia that I don’t already know.
Doctor: I must say, you certainly are a rara avis, which means—
Patient: “Rare bird,” coming from Juvenal’s sixth satire in which a good wife is said to be as rare as a black swan.
Doctor: I didn’t know that! You do indeed know a lot. But such broad knowledge would be a wonderful thing to possess. Anything you can think to ask yourself, you can answer. Anytime you feel a bit of wonder, you can offer an explanation. With such knowledge you can answer anything! Why on earth do you regard it as a problem?
Patient: I am bored out of my head! I have written half of the encyclopedia, but I can’t possibly go on, since I already know everything I’m going to say. What’s the point? You must understand, doctor, that learning new things is my greatest delight. But now I know too much, and there’s nothing for me to learn! Oh, how I wish there were something for me to learn! (breaks down in tears)
Doctor: There, there! Here, dry your tears on this handkerchief, which is either white or blue, depending on how you look at it. I see your problem, and though I have not run into it before, I think I know how to treat it. What you need, my friend, is a healthy dose of skepticism.
Patient: Skepticism? But you should be warned, doctor, that I not only know everything, but I also know the explanations for everything and all of the justifications. I don’t think skepticism can possibly help!
Doctor: Well, you may be surprised. In my experience there is always some room for doubt. What’s more, I think you will find that if you apply skeptical doubts of the right kind, in the appropriate measure, and at the right time, you will be able to transcend your great knowledge and reach a very fine form of happiness.
Patient: I guess it’s worth a shot. I’m miserable now as things are.
Doctor: Good! Now since you are such an intelligent person, I will teach you seven skeptical doubts which I am sure you will be able to apply as needed. I call them the “seven modes.”
Patient: Sounds good. But I doubt that this will help!
Doctor: See, you are making progress already! The first mode has to do with history. You say you are writing an encyclopedia?
Patient: Yes, the most comprehensive and accurate encyclopedia ever written, if I may say so myself!
Doctor: Will your encyclopedia include a history of encyclopedias?
Patient: Well, yes, I suppose it must.
Doctor: So then you will include the great, long tradition of encyclopedia writing. You will include Gregor Reisch’s Margarita Philosophica of 1496, and Paul Scalich’s 1559 encyclopedia, and of course the wonderful Cyclopaedia Ephraim Chambers published in 1728 which led to the French Encyclopédie which led to the Encyclopedia Britannica. But your encyclopedia will improve upon all of these, will it not?
Doctor: But the funny thing is that each of the authors of these older works also thought they were having the final say and that they were improving immeasurably upon the encyclopedias of the past. Why do you think you are better off in this regard?
Patient: Well, they were all smart people for their time, but I know more than they did then.
Doctor: But would they not have said the very same thing?
Patient: I guess so.
Doctor: And they were wrong by our lights. But what should we conclude from this evidence? Doesn’t history suggest that writers of encyclopedia always take themselves to have knowledge and (at least so far) have always been wrong about that?
Patient: That does seem to be the case.
Doctor: Good! So that is the first mode. The second mode has to do with culture. All of those encyclopedias I mentioned, the ones by Reisch and Scalich and Chambers, were written by western Europeans, were they not?
Patient: Yes. Reisch was born in Württemberg in 1467 and went to—
Doctor: Hold on now, the point’s been made! They were Europeans. But it would be very surprising, would it not, if there were not also encyclopedias written in many other lands such as China and India and Egypt.
Patient: Yes! Why, in China, the 1726 Chinese Collection of Pictures and Writing—
Doctor: Yes, yes, exactly! But these other encyclopedias no doubt had very different entries and very different explanations owing to the different cultures and languages and religions and philosophies and systems of science. And yet all of these non-European writers of encyclopedias also took themselves to be giving the final say and improving immeasurably upon every other effort.
Patient: Yes, I suppose so.
Doctor: And, within their own cultural contexts, they had as much reason to take themselves to have superior knowledge as you do now in your culture. Am I wrong?
Patient: No, you are right. They thought they knew everything—though their “everything” was not the same “everything” that the European writers took themselves to know.
Doctor: So that is something to consider: whether any person bound to a single culture can really be said to know everything. Or even anything! For wouldn’t anything you claim to know be understood quite differently by someone from a very different culture?
Patient: Yes, I guess that would be true. Every culture has a different way of understanding things, and to the extent they don’t square up with one another, it’s hard to be confident about what one culture claims to know.
Doctor: Onward, then, to the third mode which concerns your own brain.
Patient: And a very fine brain it is!
Doctor: One of the very best, I agree! Consider the unimaginably long history that has brought about your brain. The long process of evolution from bacteria to vertebrates including fishes and reptiles and mammals and, eventually, humans, took millions and millions of years. And it was no smooth process, as you know. There were plenty of failed starts and extinctions along the way, and plenty of accidents, both lucky and unlucky, that led to things being the way they are today.
Patient: Yes, I know this well! I have several insightful entries on evolutionary history.
Doctor: I’m sure you do. And so I am also sure you realize that our brains did not develop for the sole purpose of gaining knowledge. Our cognitive set up had to be just good enough to allow our ancestors to reproduce before dying. And that doesn’t necessarily require an organ that is excellent at knowing. It only requires an organ that isn’t a total disaster, at least in the department of making babies.
Patient: I hadn’t heard it put that way, but you’re right. Evolution just selects for reproductive fitness, not necessarily for epistemic fitness.
Doctor: Exactly. So that means that, for our knowledge, we are relying on an organ that wasn’t exactly evolved for being good at knowing. We would be skeptical of the use of any device that wasn’t designed for the purpose we’re using it for, wouldn’t we? So shouldn’t we be skeptical of our own brains when it comes to knowing things?
Patient: I guess so … hey, wait a minute! It’s our brains that are telling us this! Our brains figured out evolution by natural selection—well, Charles Darwin’s brain figured it out, at any rate—and our brains have deduced these skeptical consequences. So don’t we have to trust our brains in order to not trust our brains?!
Doctor: Now you’re getting that hang of it! It’s hard to know what to believe, isn’t it?
Patient: I feel dizzy.
Doctor: Here, have another sip of this stuff that certainly seems to be water. Now let’s turn to the fourth mode which is related to what we were just talking about. I call it the animals and aliens mode. Human brains evolved in ways that have ended up helping human beings lead human lives, right? But the same is true for ape brains, dolphin brains, elephant brains, even frog brains—each species evolved brains that suit the lives those species live.
Patient: Yes, it’s the same story across the board.
Doctor: And there is so much interesting variation! Think about bats with their echolocation, or how pit vipers can see heat. And did you know that, while we have only three sorts of photoreceptors in our eyes, mantis shrimp have as many as sixteen different kinds?
Patient: Indeed! They can see deep ultraviolet light, as well as far red light, and polarized light.
Doctor: Just think about the sorts of encyclopedias these animals would write! What they experience is so different from what humans experience, but their experience is just as valid, wouldn’t you agree?
Patient: Sure. In many cases, the animals experience much more than we do.
Doctor: And I presume you are familiar with all of the arguments suggesting that there almost certainly is life elsewhere in the universe.
Patient: Of course! There must be, given how enormous the universe is. It is statistically quite certain that life has evolved on countless other planets.
Doctor: Some of those aliens have probably written encyclopedias as well! And in all likelihood, those aliens would have evolved in very different ways from any life on earth. So what they would claim to know would be even more different than what our own bats and vipers and mantis shrimp would claim to know.
Patient: Yes, it would be impossible for us to conceive what they would think they knew.
Doctor: But there is no reason to think any less of them for that, is there?
Patient: Of course not! Okay, okay, I see the point: animals and aliens would have knowledge that is radically different from human knowledge, and every bit as valid, if not more so, which means human knowledge cannot be the be-all and end-all.
Doctor: I could not have said it better myself! Are you ready for the fifth mode?
Patient: It is hard to believe there’s even more doubts to consider!
Doctor: You can be sure of it! Set aside the last two doubts about our brains and the brains of animals and aliens. Suppose we could assure ourselves that our brains are in fact excellent trackers of truth. Still, a person as educated as you must surely realize that there is hardly anything to put into an encyclopedia that isn’t contradicted by some other expert somewhere?
Patient: Don’t I know it! You know, as a hobby I routinely correct entries on Wikipedia, and boy have I gotten into fights—sometimes even over the most trivial things!
Doctor: It seems like there is no bit of knowledge that isn’t contested by someone. But often, that someone has some reasons for raising their objections, especially if the matter has big consequences. No one cares much about the exact temperature outside the Poughkeepsie courthouse at noon, but start talking about raising the minimum wage, and hoo boy!
Patient: Yes sir!
Doctor: So, it would seem, on a great many matters, experts disagree. And we know from the first mode, the one based on history, that experts can be very wrong. So if experts, who dedicate much of their careers to understanding important things, can disagree with one another, and may well be shown to be wrong later on, then what hope for getting things right do the rest of us have?
Patient: Not much. I mean, I know how hard it is to be an expert since I am one on nearly everything. But there are always people disagreeing with me, and sometimes, if I’m honest, I’m not sure they’re wrong!
Doctor: Interesting, isn’t it, that experts, who represent the highest knowledge a human can have on a topic, end up serving as a reason for being skeptical, even about that very topic!
Patient: Well, only because experts so often disagree! It makes it hard for a nonexpert to know what to believe or whom to trust.
Doctor: Exactly. So let us consider next the sixth mode which is based on logic.
Patient: Aha! I am an expert logician!
Doctor: So I gather! And where did you learn logic?
Patient: I attended a very fine school in Des Moines.
Doctor: Des Moines? And where is that?
Patient: In Iowa!
Doctor: And where is that?
Patient: In the United States, of course.
Doctor: And where is that?
Patient: Is this a trick? It’s in North America. And before you ask, that’s on planet Earth, in the solar system, in the Milky Way galaxy!
Doctor: And where—
Patient: In the Virgo Cluster, which is in the Laniakea Supercluster, which is in the universe!
Doctor: Good! And where is the universe?
Patient: What sort of silly question is that?! No one can answer that!
Doctor: Ah, so you don’t know where you learned logic.
Patient: Uh … what???
Doctor: I’m just having some fun with you, of course, calling to your attention the idea of a regress, which is a long chain of questions either without an end or with a big question mark at the end. A regress suggests that if you can’t answer the long chain of questions, you don’t really have knowledge of what’s at the tail end of it. Here’s how it’s relevant to your case. Didn’t you say earlier that you not only knew everything, but also all of the explanations and justifications for everything?
Patient: Yes, I did say that! Though now I’m becoming less sure …
Doctor: So, if I asked you about something you know—let’s say, about some event in the War of 1812—you could tell me about the event, and you would be able to give me evidence for believing what you do about that event?
Patient: Yes, I would! I am very scrupulous.
Doctor: And so then, you could give me reasons to believe that evidence? Evidence for the evidence, so to speak?
Patient: I think so … well, to some extent…
Doctor: And evidence for the evidence for the evidence?
Patient: Hold on! Explanations have to stop somewhere!
Doctor: But where? With things for which you have no evidence?
Patient: Well, yes, I mean, I guess so…
Doctor: But this means everything you believe is ultimately based on things for which you have no evidence!
Patient: Just because there’s no evidence for something doesn’t mean I shouldn’t believe it!
Doctor: Come again?
Patient: Well, just because I have no reason to believe them doesn’t mean I have no reason to believe … uh, wait a minute. I’m not sure what I’m saying ….
Doctor: Excellent! See? Your swelling of knowledge is already going down!
Patient: I feel everything slipping away …
Doctor: Isn’t it a nice feeling? All those things you thought you knew and had to keep track of and worry about are all slipping away. No knowledge, no worries! This is the perfect point at which to tell you about the seventh mode, my favorite, which I call the forever open alternative.
Patient: What’s that?
Doctor: All the doubts we have been through have had something in common: they have all indicated that there could well be something we hadn’t thought of. Maybe it’s a future discovery, or the discovery by another culture, or by animals or aliens, or something our brain isn’t picking up, or some further question we hadn’t thought to ask. The forever open alternative is the general possibility that there is something important we haven’t considered yet. Who knows why! The world is such a big, complicated place, and we are so tiny and live such short lives that it would be incredible if there weren’t extra complications we have not considered!
Patient: That seems unavoidable. It’s always possible that things are more complicated in ways we have not even imagined!
Doctor: Yes, and maybe we can’t even see the ways in which they are more complicated! The forever open alternative is simply the recognition that we may not know as much as we think we do. It’s the essence of skepticism, really. There’s always an open possibility that we just don’t really know what we think we know.
Patient: Doctor, I think you have cured me! I feel like I can diminish my confidence in everything I used to believe!
Doctor: Glad to hear it! You will learn through experience which mode to use in each case, since some will be more effective than others, depending on what you are doubting. But if you apply yourself, you find you are able to place yourself in a blissful state of not knowing. You will balance yourself between each claim and its denial, neither affirming nor rejecting either one, but floating above them all. And that, my friend, is a happy state of mind!