10. WHAT CONSTITUTES SCIENTIFIC EVIDENCE?

A persistent theme throughout the conference is the criteria for proof of an argument. How do we know what we know? When is it reasonable to generalize from particular observations? How do we deal with exceptional cases? Should testimony—allowable evidence in law—be completely discounted by science? How can the scientific method, which relies entirely on “objective” observation, begin to account for the subjective experience of consciousness? Both science and Buddhism rely on methods that constantly test belief against empirical experience, but Buddhism allows subjective experience as valuable evidence in the study of consciousness.

DALAI LAMA: There are certain people who feel they have out-of-body experiences while dreaming.

ALLAN HOBSON: This has not been studied in the laboratory, but it is easy to imagine how such a state could arise since it is possible to hallucinate practically anything during dreaming.

DALAI LAMA: There are accounts of people experiencing this sense of leaving their body, actually perceiving things in the external world, and later being able to recall events that presumably took place there, even to the point of being able to read a book in someone else’s house. Has there been no scientific investigation of this type of testimony?

ALLAN HOBSON: That is correct, there has been no scientific investigation of these. But I would like to discuss this issue because I think that the issue of precognitive dreams, out-of-body experiences, and claims of previous lives, all have a problem in common for science. And in discussing this issue, I want to make clear, first, that my mind is not closed. But I am a scientist. So the opening in my mind is probably quite narrow!

Now this narrow opening, which is guarded by skepticism, is a crucial part of our scientific mental discipline, I believe. It is as important to our understanding of the truth as is inspiration. It is not a wish to ignore the truth. It is a wish to critically test belief against experience. So in that spirit, I think that Western science has a lot to offer, as a tool, and not as a weapon.

DALAI LAMA: Yes, very good. Beautiful.

ALLAN HOBSON: The question is: How can we advance any of these claims above the status of what we would call testimony and anecdote?

DALAI LAMA: The best thing is to experiment on those people who make these claims.

ALLAN HOBSON: That is one way. But then the question becomes: What kind of experiment? But before we get to that, let me add one more point that I think is important. In a court of law, testimony is important as evidence.

DALAI LAMA: Is it not held in science, that if some event or experience is true for a normal person, it must be true as well for all other normal persons?

ALLAN HOBSON: That generalization is not one of the demands that one makes. It is true that there can be exceptional individuals. We know that not everyone is a lucid dreamer, for example.

PATRICIA CHURCHLAND: It would have to be that every similar person must have that capacity. But sometimes it would be hard to tell whether two or three persons are similar in the right respect. Yet it would have to be that everyone who was similar to that person would have that property or share that experience.

ANTONIO DAMASIO: Or at least we need to have one example that would be convincing. If we would find proof that a cat can fly, we would not need to see any other cat fly. If only one had verified flight capability, we would be able to refute the statement that all cats cannot fly and we could deny that that’s a true statement. All you need is one solid example of something and you have proof.

ALLAN HOBSON: The fewer the examples, the stronger the evidence must be.

DALAI LAMA: Yes, that’s right.

ALLAN HOBSON: Generalization will help you, even if the effect is weak, because generalization is robust and widely distributed. So if you are going to rely on individual cases, exceptional individuals, then the evidence must be particularly convincing to overcome skepticism—and the skepticism in our minds is very marked, because there have been so many claims in the West, as in the East, of this sort of experience, which, when put to critical test, do not convince us as constituting evidence. It constitutes testimony, but not evidence.

ROBERT LIVINGSTON: The history of science is largely an account of disabusing ourselves of mistaken speculative suppositions. Elan vital and phlogiston are but two examples, each widely adhered to for decades.

ALLAN HOBSON: There is another important point I would like to discuss concerning method. Dr. Judd pointed out to me yesterday that there is an important distinction between a retrospective experiment and a prospective experiment. Maybe, Lew, you would comment on that and illuminate the point.

LEWIS JUDD: I think that in the Western scientific tradition, the basis of the ultimate, so-called scientific truth, is really created when you start from a certain point, establish a set of experimental conditions, and then watch it unfold. This is in contrast to looking back from a point to find evidence by which to establish scientific truth. So, for example, in one of the issues that was raised yesterday, about the memory of these two little girls of their past lives, we were saying that there are various ways one might explain that away. Not necessarily to discount it, but ways that would survive skepticism.

On the other hand, if one were to conduct a prospective experiment, starting from scratch, as to whether the information we are gathering today might play out in future lives, there might be a way to test future Dalai Lamas as to whether or not they remember neuroscience information that they acquired on this day, ten years from now, or fifty years from now, or five hundred years from now.

ANTONIO DAMASIO: May I add that any observations made up to now can be the basis for constructing a hypothesis, rather than being immediately taken as evidence. With that hypothesis, with that theory, then we can proceed to set up experiments deliberately to test whether the evidence supports the hypothesis and see just how strong the evidence is. In experimental research, we tend to go that way. An observation, an idea, leads to a hypothesis, a theory is constructed, and then we conduct experiments and decide how strong the hypothesis really is.

It tends to be the case that we never prove anything. In fact, all that we can do, very modestly, is to determine whether or not our experimental results are strongly in favor, or slightly in favor, or definitely against the hypothesis. We decide on the weight of all pertinent evidence.

LEWIS JUDD: Is Your Holiness familiar with the concept of prospective design of experiments? For example, let’s say we have a hypothesis, a theory, that if a certain drug A is given to an individual it will suppress certain symptoms. That’s the hypothesis. One would then design an experiment to give the drug or medication under controlled circumstances and measure the effects to establish whether the drug had the anticipated or other effects. To make the evidence more foolproof, you could conduct double-blind experiments where persons administering the drug and those measuring the effects would not know whether the individual were actually receiving that drug or some substitute drug or a placebo. There are a number of traditional ways that can be used to avoid subjective impressions creating biases and introducing noise into the evidence.

DALAI LAMA: This issue is very clear.

ALLAN HOBSON: Again, I wish to emphasize the point about creative use of skepticism. What Western scientists do, that to you might appear to be negative, is really their attempt not to be fooled. In other words, what a Western scientist does in constructing prospective experiments is to try to set the conditions in such a way that all alternative explanations will be eliminated and that his hypothesis can be disproved. Thus, an important spirit of science is to be open to giving up the hypothesis. That’s an important attitude, and difficult to fulfill.

DALAI LAMA: I suspect that sometimes scientists, too, tenaciously cling to a hypothesis so much that they still adhere to it, regardless of contrary evidence.

LEWIS JUDD: Yes.

ALLAN HOBSON: Skeptical investigation is very important.

ANTONIO DAMASIO: Actually, one measure of the quality of a scientist may be how readily he gives up his cherished hypotheses. In fact, we are consistently adhering to very good ideas which may in a decade or two be clearly shown to be wrong. And there are some people who simply can’t give them up and will cling to them.

DALAI LAMA: On one occasion, I met a group of scientists who introduced themselves to me one after the other, and one of them told me, “I am a fanatical materialist. I will not accept the existence of mind.” So my question is, for these extreme, radical materialists who refuse mind’s existence, insisting that it simply does not exist, why are they saying that? What do they mean by the term mind?

PATRICIA CHURCHLAND: What they mean by mind is the brain. That’s what they mean.

DALAI LAMA: Nobody can deny the existence of the brain.

PATRICIA CHURCHLAND: When they said the mind doesn’t exist, they mean there isn’t something spirit-like that is independent of the brain. They think of perceptions or thoughts or dreams as processes of the brain. And that was really what I was talking about yesterday. There is a common idea that there is a nonphysical soul, but when you look more closely at what neuroscience has discovered it looks like there is only the brain.

DALAI LAMA: Even in Buddhism there is no notion of a self-sufficient, self-supporting “I,” self, soul, or ego. This is thoroughly refuted. Buddhists do assert the existence of awareness, but to use the term soul in a Buddhist context is misleading, because Buddhists don’t use the term and by and large refute the existence of a soul.

PATRICIA CHURCHLAND: But do you think that there is something, I am not sure what to call it—a kind of awareness that can exist independently of the brain? For example, something that survives death?

DALAI LAMA: Generally speaking, awareness, in the sense of our familiar, day-to-day mental processes, does not exist apart from or independent of the brain, according to the Buddhist view. But Buddhism holds that the cause of this awareness is to be found in a preceding continuum of awareness, and that is why one speaks of a stream of awareness from one life to another. Whence does this awareness arise initially? It must arise fundamentally not from a physical base but from a preceding continuum of awareness.

LEWIS JUDD: So it is independent of brain function.

DALAI LAMA: The continuum of awareness that conjoins with the fetus does not depend upon the brain. There are some documented cases of advanced practitioners whose bodies, after death, escape what happens to everyone else and do not decompose for some time—for two or three weeks or even longer. The awareness that finally leaves their body is a primordial awareness that is not dependent upon the body. There have been many accounts in the past of advanced practitioners remaining in meditation in this subtle state of consciousness when they died, and decomposition of their body was postponed although the body remained at room temperature.

LEWIS JUDD: How would you know that their brain function had completely ceased?

DALAI LAMA: This would be good to check out with the instruments of Western science. Last year there were two advanced practitioners, one of whom remained in that state without his body decomposing for four days, another for about ten days. But unfortunately, on those two occasions there was no physician on hand to conduct the test. We have to make arrangements before such things happen. Hopefully, we will have equipment and an expert available to fulfill this objective.

ALLAN HOBSON: There again, you see, skepticism would immediately try to imagine other explanations for the same phenomena, namely that the brain might still be active at a low level. We know that there can still be valid neuronal activity even when the EEG is absolutely flat. There still may be neurons down in the brain stem which are firing. This happens, for example, in hibernation.

ROBERT LIVINGSTON: This is a difficult experiment. Western science has dealt with brain death for quite a while. Brain death is very tricky to establish. Whether brain death can be established beyond peradventure of doubt may be crucial as to whether you continue to provide life support for that individual, or not. I think that if you had a person dying in that way, it would be very difficult to decide when you might have reached some level of “subtle awareness.”

DALAI LAMA: The methods for realizing this state of awareness are set forth in Buddhist treatises on philosophy and meditation. We follow the methods and we see outward signs, but we can’t tell for certain what they indicate. What we see externally is that the meditator, who is well into the dying process, is sitting upright in meditation, with no physical movement, heartbeat, or respiration. And he stays like that for four to ten days.

Prior to the cessation of breathing and heartbeat, the body is already degenerating because of illness. But now, following the cessation of breathing and heartbeat, the metabolism, as far as we can tell on a gross level, becomes restored somewhat. These interpretations are based on external observations.

ALLAN HOBSON: And they are signs which imply the continuing existence of the body. We would say skeptically that the brain is probably still alive. You would say the practitioner’s awareness persists in some subtle but not nonphysical way.

DALAI LAMA: Yes. You are saying that some part of the brain stem is still functioning?

ALLAN HOBSON: That is an alternative explanation.

LEWIS JUDD: It is a hypothesis that needs experimental testing.

DALAI LAMA: Good, let’s do it!

DALAI LAMA: In Buddhism we speak of three types of phenomena: First, there are evident phenomena that are perceived directly.

Second, there are slightly hidden phenomena, which are not accessible to immediate perception. There are differences of opinion on this even within Buddhist philosophy. Generally speaking, we think this second type of phenomena can be known indirectly by inference. One example of something known by inference is that anything arising in dependence upon causes and conditions is itself subject to disintegration and momentary change. This momentary change is not immediately evident to your senses. You can look at something with your eyes, and it does not appear to be changing right now, but by inference you can know that it is momentarily changing. This is an example of the second category of phenomena.

Third, there are very concealed phenomena, which cannot be known by either of the two preceding methods. They can be known only by relying upon testimony of someone such as the Buddha.

Leaving aside the third category, do you as scientists accept the first two categories?

PATRICIA CHURCHLAND: The first two categories seem to be roughly the way Western scientists also think about them.

ALLAN HOBSON: The more we know about phenomena, the less we need the third category. My contention would be that your knowledge about the first two categories, and especially the second, is limited to the degree that we impute the third category. As our knowledge of the second category grows, our need for the third category will diminish.

DALAI LAMA: The same could be said about the second category as well. If we can increase our ability to see things perceptually, then the second category diminishes.

ALLAN HOBSON: Absolutely. That’s the task of science.

DALAI LAMA: This threefold categorization—in the Buddhist context—is not coming from some inherent differentiation among phenomena, but rather from the limitations of our capacity for awareness.

For example, something that may be slightly concealed for me may be evident for another person. What is occurring in my mind right now is to me evident, but for you it is concealed. Unless I tell you how I feel at the moment, there is no way for you to know. Apart from that testimony, there is no access to it.

PATRICIA CHURCHLAND: Yes, except that we can rely on other aspects of your behavior. That is, if you were wincing or holding your jaw, I would infer that you had a toothache even if you didn’t say so. Thus, there would be other aspects of your behavior, body language, and so on, that would give us information. Your testimony is of course important, but it is not decisive. You could be playacting.

ROBERT LIVINGSTON: It is the problem of a secret. You can hold a secret, and nobody can discover that secret.

DALAI LAMA: Here is my point: What do we have to say right now about those phenomena that can be known only by testimony, such as what I am thinking right now?

LARRY SQUIRE: That is a practical statement. Neuroscience would say that, in principle, with enough technology, these things would become accessible—for example, if there were techniques by which to measure fine structural activity in many parts of the brain directly and simultaneously.

ALLAN HOBSON: Let me give you one very strong example. I could tell that you were dreaming even when you didn’t know you were dreaming.

DALAI LAMA: Can you tell what I am dreaming?

ALLAN HOBSON: Wait a minute, wait a minute, be patient!

ANTONIO DAMASIO: One could describe the agenda of science—what we want to do, and in a very modest way what we are already doing—is to reduce our reliance on that third category. It is obvious that we are not going to complete this for a very long time, but what we want to do is to remove more and more issues from the third category and move them into the first two categories.

LEWIS JUDD: And from the category two into one. We are always pushing issues into category one. That’s the importance of science.

ANTONIO DAMASIO: The process is always shifting, based on better observations, better technology, and better theory.

DALAI LAMA: I am speculating that perhaps as a result of increases in scientific understanding and technical advances, things which might have been extremely concealed, as Buddhists talk about these categories, might even become clearly evident; for instance, like the earth being round. Centuries ago, if you believed that, it would be only on the basis of testimony, because somebody said so. Now you can see it with your own eyes, in pictures.

ROBERT LIVINGSTON: I can give you a concrete example of the progress of our learning about how consciousness and personality depend on detailed brain structures.

We studied scores of postmortem human brains, from people who had experienced no known neurological or psychiatric illnesses. By slicing whole brains at microscopically thin intervals and imaging each freshly cut surface from a fixed camera position, we obtained motion pictures in perfect registration of each successive surface all the way through each brain.

Examining these images, we found that the surface contours and internal structures are vastly different from each brain to any other. The differences we found are grossly obvious. There are twofold differences in areas of cortex that have important, discrete functions, and similar gross differences in subcortical regions. We found every brain to be unique, just as our faces are. But the differences in brain structures are deeply meaningful in respect to perceptions, memory, motor and emotional skills, judgment, personality, and character.

We made computer reconstructions of one brain so that the principal structures could be seen three-dimensionally and dynamically rotated and moved about for purposes of demonstration in a documentary film. We believe that computers and suitably expanded memory management systems will allow detailed quantitative comparisons to be made of differences in microscopic detail among many whole human brains.

Comparisons between detailed life histories and the detailed structures of the corresponding brains will allow what our friends call “endophrenology.” This technique would permit correlations between details of brain organization and human qualities of consciousness, perception, judgment, temperament, and behavior. Of course, such data can also be used to compare magnetic resonance images of living brains, and thereby obtain even more fascinating subjective correlations.

At some point we should be able to say that certain notably expanded structures in a particular brain suggest that this individual likely had great musical ability, and so forth. Perhaps by observing brain structures that are especially noteworthy in certain remarkable individuals, we shall be able to identify brain morphology that is characteristic of compassion. I confidently predict a branch of neurosciences that will disclose features of the human brain, presently largely concealed, that relate to both our inner subjective and our outer worldly life experiences.

DALAI LAMA: Although it is difficult to pinpoint the physical base or location of awareness, it is perhaps the most precious thing concealed within our brains. And it is something that the individual alone can feel and experience. Each of us cherishes it highly, yet it is private.

ALLAN HOBSON: But then, when we share, if we dare, what is going on, it usually tends to reveal many things in common. So what appears to us to be inevitably private is in fact quite generally shared.

ANTONIO DAMASIO: It is much more than that. It has tremendous commonality. It is interesting to think about differences and similarities in both brains and minds; it depends on your perspective. On the one hand, there are differences in every brain. Each is unique. At the same time, they are generally similar. The same with our spirits, we are remarkably similar in spirit. That is how you can have human sympathy, empathy, and cross-cultural compassion.