All paths of practice must begin with a simple question. How do we know where to start? How do we know what is correct to believe? In the Cankī Sutta (Majjhima Nikāya 95; I rely on the Ñāṇamoli/Bodhi translation), the Buddha debates a young Brahmin named Kāpaṭhika, who has faith in the Vedas as his religious guide. In opposing the boy’s approach, the Buddha gives a detailed overview of how one is supposed to validate any proposed dhamma. The key question here is how to ensure that we not choose false teachings. How are we to “preserve truth” (15) in our beliefs?
The Buddha notes (14) that there are five ordinary bases for truth-claims, and that all of them “may turn out in two different ways”; that is, they may turn out true or false, and none of them is guaranteed to preserve truth. These are:
(1) Blind faith,
(2) Simple personal preference,
(3) Oral or written tradition,
(4) Logical reasoning,
(5) Reflection and acceptance.
One may hold a view based on any of these five ways, he tells us, and yet that view may be either true or false. Of the five, the first three are uncontroversial. The most in need of exegesis are the last two. To explain: for number four, since logic is famously truth-preserving (and indeed since the Buddha himself resorts to logic in showing how truth can actually be preserved, later in the Sutta), the point here is one of finding the right premises. Simply showing that our conclusions are derived logically is no guarantee of the truth of those conclusions.
Similarly, number five, reflection and acceptance, will eventually prove to be a good summary of the Buddha’s own view of the subject (20). Presumably here what he means to point out is that not all reflection is of sufficient care and thoroughness to reveal the truth. So simply having reflected upon something is no guarantee that it is true.
So, then, how are we to preserve truth? The Buddha begins simply: a person who has faith in something preserves truth by saying “I have faith in this thing”. This is a small logical deduction, and is indeed truth preserving. However, as he notes it doesn’t discover truth, it only restates faith.
In order to discover truth, the Buddha outlines a lengthy, sequential series of steps, which I will not go into in detail. The question which instead will concern us here is whether those steps also guarantee truth-preservation.
So a teacher presents us with a dhamma claim. How should we begin to evaluate it? The series begins (as in MN 47) with an investigation into the person who presents the claim. What is the teacher’s own behavior? Does he or she display states of greed, hatred or delusion, such that they might try to lead us astray? If so, then we can reject the teaching as likely to be harmful. If not, then we are justified in placing faith in that teacher, as the start of our path into the dhamma.
There are problems with the Buddha’s criterion, however. His evaluation does not guarantee the truth of our teacher’s claims, for three reasons. First, this strategy is an example of a fallacy known as “ad hominem“: truths about the person stating a claim are irrelevant to the truths of the claims the person is stating. Or to put it another way, even the greediest, most hateful or deluded person on earth may speak truthfully. We cannot with certainty reject an assertion based upon the bad behavior of the person making it.
Second, it does not follow that someone who is free from greed or hatred necessarily knows things that are truth-revealing. One free from greed or hatred may be ethically laudable, but may otherwise know little. What about someone who is free from delusion? That is a harder matter, since it isn’t clear what behavior is supposed to tell us that a teacher is free from delusion. Ñāṇamoli and Bodhi translate the passage so as to put the matter in terms of “obsession” (19): to tell if our teacher is not deluded, we look to see that he or she is not mentally obsessed in harmful ways. But even so, one who speaks and acts in ways free from harmful obsessions is not guaranteed to be in possession of the truth.
We do have to admit that lacking these unskillful traits is a good thing in a teacher: it makes it more likely that he or she will not try to lead us astray. But it does not guarantee that our teacher’s dhamma will be true and informative.
Thirdly, there is the problem of our own imperfection. In order to know with certainty that our teacher is without greed, hatred or delusion, we must be perfectly able to gauge those states in others. But we are not. So we may be led astray by overestimating the worthiness of our teacher.
Although the Buddha gives further criteria for evaluating a dhamma claim (that it should be profound, hard to see, peaceful, and so on), there may be many, mutually exclusive teachings that fit those criteria. Further, until and unless we are fully enlightened ourselves, how accurate is our opinion about profundity and peacefulness likely to be?
Since the first step in this process of evaluating teacher and dhamma is not guaranteed to preserve truth, the rest of the steps that follow (faith in the teacher, visitation, and so on, (20)), are also not guaranteed to preserve truth. It remains possible that we have chosen the wrong teacher due to our own inability to judge the teacher as worthy, the teaching as wise, or due to the teacher’s being relatively ethically pure but ignorant. And any chain of reasoning is only as good as its weakest link.
There is a further issue, raised by Bhikkhu Bodhi in his oral discussions of the sutta. The process of searching for truth begins with faith. For the Buddha this is not blind faith, instead it is based on a studied trust in one’s teacher. Nevertheless the faith itself presents us with a problem: might it actually color the experiences we have during the course of our learning? So, for example, Christians will learn from Christian teachers to have faith in God and an immortal soul, and hence in their deep meditative states they will seem to see their eternal self and the God to whom they direct prayer. Hindus learn from their gurus about the non-dual nature that makes their souls identical with Brahman, and then witness the same in meditation.
The claim in each case is that direct experience verifies the claims; however different followers in different traditions have different sorts of direct experience. Each supposedly verifies the truth of their claims. But each of the claims is mutually exclusive: some claim experience of an eternal soul, others claim there is no such experience. Some claim experience of an eternal God, others claim there is no such experience. Or is it that only Buddhists are subject to anatta? That is hardly credible.
How do we adjudicate the difference? Who, if any among them, is right? In the Buddha’s terms, how do we preserve truth, given that direct experience based on faith — even reasoned faith — “may turn out two different ways”?
I don’t have a good answer to this question. I don’t believe there is any way to “preserve truth” with absolute fidelity, since no matter how good one’s reasoning (limited examples aside), one’s premises may always prove false. However there is more we can do: expand the Buddha’s own investigative criteria. Instead of accepting our own, untutored opinion about a teacher, we might ask around and get more opinions about him or her. What do the wise people say? What do the critics say? What other information might people have turned up? Although this is also not guaranteed to preserve truth, at least it brings in a wider base of evidence and more pairs of eyes.
Personal, subjective experience, the behavior of a teacher, no matter how compelling, is thin on the ground. (Who among us will ever have a truly enlightened teacher, anyway?) Examples from different faith traditions show that experience can lead astray. In order to do our best to preserve truth, we also need objective or intersubjective testing: we need to design experiments to eliminate the faith-bias of the practitioner. We need to gather other people, perhaps antagonistic, to redo experiments and verify teachings. We need open debate and discussion among people of all backgrounds.
We need to broaden the Buddha’s own investigative techniques to encompass the methods of modern science, and to embrace scientific consensus in our search for what is justified to believe. This does not mean we must restrict our beliefs simply to what is accepted by scientific consensus: nobody can live that way. It is no matter of science that I can find my way to the grocery store and back. But it does mean that teachings must be weighed against science, to see if they stand or fall. The Dalai Lama has said no less.
Of all the great religious and philosophical traditions, few are as in tune with a contemporary scientific understanding of the mind and its place in lived experience as was the Buddha and his dhamma. Contemporary Buddhists typically use the results of modern science to validate the three marks of existence against theistic claims of an eternal soul. What’s to fear in pushing farther? The Buddha himself held the dhamma up to inquiry and examination. We should do no less in our search to “preserve truth”.
Since for the novice — or the experienced practitioner with ‘beginner’s mind’ — the methodology outlined by the Buddha in the Cankī Sutta does not guarantee to preserve truth, the correct attitude of the practitioner must remain one of open skepticism. This is not to say one cannot accept much of the dhamma with a high level of confidence. What it means is that one must always weigh the dhamma against the sciences, since the sciences are a more epistemically secure foundation for knowledge: they do not involve faith in a single teacher, nor the assumption that a teacher who is well-behaved is thereby in possession of the truth, nor the worry that we as imperfect judges may not be prepared to determine the worthiness of our teacher.