This discourse from the Majjhima-Nikāya, or Middle-Length Discourses, shows us the Buddha in dialogue with a monk called Māluṅkyāputta, a person for whom metaphysical views are evidently important. What the Buddha says to Māluṅkyaputta tells us exactly why speculative views are not relevant to the spiritual life, and it does so by means of a memorable simile. There are several discourses in the Pāli canon which feature him, and in one he appears as an old man who approaches the Buddha to get a pithy, direct teaching about the nature of reality. The Buddha gives him one, and the old monk soon reaches awakening. So Māluṅkyāputta, we might say, was someone who was prone to take the wrong approach to the meaning of the Dharma, but who certainly got it in the end.
The discourse begins with Māluṅkyāputta on his own, in meditation, thinking about things. He comes to the conclusion that he needs to find out what the Buddha thinks about certain metaphysical issues that the Buddha appears to have left unexplained or undeclared (avkyākatāni), and he decides that if the Buddha does not engage in these issues to his satisfaction, he will leave the monastic order. He visits the Buddha and asks him whether:
- the universe is eternal;
- the universe is not eternal;
- the universe is finite;
- the universe is infinite;
- the soul and the body are identical;
- the soul and the body are different;
- a sentient being exists after death;
- a sentient being does not exist after death;
- a sentient being both exists and does not exist after death;
- a sentient being neither exists nor does not exist after death.
This is a standard list found in the Pāli discourses, and it presumably represents the kind of things speculative philosophers of the Buddha’s time thought about. These days our questions might be slightly different. We might wonder, for instance, whether:
- the universe will keep on expanding for ever
- the universe will at a certain point contract again
- there is life elsewhere in the universe
- there is life only on planet earth
- the mind is produced by the brain
- the mind is something apart from the brain
- there is a God
- there is no God
- there anything about us that survives after death
- nothing about us survives after death
Who could deny that such issues are not fascinating and difficult? Indeed, much academic research – perhaps the entire life-work of certain philosophers or theologians – is concerned with trying to make some progress with these issues. But when Māluṅkyāputta puts his case to the Buddha, the Buddha is very uncompromising. He calls Māluṅkyāputta a foolish man and gets him to admit that in fact he, the Buddha, had never promised to engage with such issues; Māluṅkyāputta might try to get the Buddha to explain these unexplained or undeclared (avyākatāni) issues, but he would die before the Buddha would explain them.
It might appear that the Buddha is himself taking up a philosophical position here, something like a Buddhist version of Kant’s critique of pure reason, which set limits to what we can know by thinking along. But I doubt that this is the case. To understand the Buddha’s strong metaphysical reticence, I suggest that we consider what Māluṅkyāputta was looking for. He was looking for certainty – for definite answers. For someone like Māluṅkyāputta, as for many people of a philosophical bent then and now, metaphysical certainty is associated with a kind of existential comfort, of knowing one’s place in the nature of things. Perhaps for other sorts of people, other sorts of fantasies provide comparable existential comfort. And a certain degree of progress in metaphysical certainty, and hence in existential comfort, is possible.
But this is not the point of the Dharma. The Buddha makes this point with one of his brilliant extended similes. This one is generally known as the simile of the poisoned arrow:
Suppose, Māluṅkyāputta, that someone was shot by an arrow smeared with poison, and their friends and companions, family and relatives, had a surgeon attend, but that person were to say, I shall not have this arrow pulled out until I know exactly by whom I was shot, whether ruler, priest, trader or labourer. Or they were to say, I shall not have this arrow pulled out until I know exactly by whom I was shot, what their name and what their clan… whether they are tall or short or medium height… whether they are black-skinned, dark-skinned or golden-skinned… in what village or town or city they live… until I know by which bow I was shot, whether a longbow or a crossbow… until I know by which bowstring I was shot, whether it was of plant-fibre, reed or milk-leaf… until I know by which arrow-shaft I was shot, whether it was of natural wood or of cultivated… whether the arrow-shaft was tipped with feathers from a vulture, a heron, a raven, a peacock or a stork… whether the sinews that bound the arrow-shaft were from a cow, a buffalo, a lion or a monkey… until I know by which arrow I was shot, whether its head was sharp-edged, barbed, made of iron, toothed or leaf-shaped. Māluṅkyāputta, all this would remain unknown to that person, and they would die. Likewise, Māluṅkyāputta, anyone who says, I will not live the spiritual life under the Blessed One while he has not explained to me whether the universe is eternal or not [and the other metaphysical questions] – all this would remain unexplained by the Realised One, and that person would die.
It is important to notice that the various questions are not in principle unanswerable, but that they are not the right questions to be asking. Likewise, what the Buddha does explain and make known, as he goes on to say, is the conditions whereby suffering and unsatisfactoriness (dukkha) arise, and how these conditions can be brought to an end. Metaphysical questions are in this sense just irrelevant to the spiritual life as taught by the Buddha.
I notice from this discourse that the Buddha does not tell Māluṅkyāputta what to think. Māluṅkyāputta, being someone who likes to think about things, would probably not appreciate being told what to think. Instead, the Buddha gives Māluṅkyāputta direct guidance on how to think. He points Māluṅkyāputta away from the search for certainty to the possibility of living with metaphysical uncertainty. Such a strategy is counter-intuitive for many of us. It means putting aside questions and issues which are self-evidently connected with a knowledge of the true nature of things. The reason for this strategy is that by doing so we come to a better understanding of the situation we are in, the situation which has prompted our questioning and our longing for certainty. We might say that the Buddha recommends to Māluṅkyāputta that he cultivate what the poet John Keats called ‘negative capability’, which is ‘when a man is capable of being in uncertainties, mysteries, doubts, without any irritable reaching after fact and reason’.
Negative capability is that capacity which makes conscious our longing for certainty and our desire for existential comfort, and turns it around. Instead of putting effort into finding the answers to metaphysical questions, we put our effort into understanding our present experience, with its uncertainties and its sufferings, which have their causes and conditions, and which the Buddha’s teaching is concerned with coming to know. The Buddha summarises all this to Māluṅkyāputta in the conclusion to the discourse:
Therefore, Māluṅkyāputta, you should remember what I have not explained as what has not been explained, and remember what I have explained as what has been explained. And what, Māluṅkyāputta, have I not explained? Whether the world is eternal [or not eternal, whether infinite or not infinite, whether the soul and body and different or identical, and whether a sentient being exists, or does not exist, or both, or neither] has not been explained by me. And why have I not explained this? Because, Māluṅkyāputta, it is not profitable, it is not a starting point for the spiritual life, because it does not conduce to disenchantment, to dispassion, to cessation, to peace, to higher knowledge, to full awakening, to nirvana; therefore I have not explained it.
And what, Māluṅkyāputta, have I explained? That here there is suffering, Māluṅkyāputta – this I have explained. That there is an origin of this suffering – this I have explained. That there is cessation of this suffering – this I have explained. That there is a practice leading to the cessation of this suffering – this I have explained. And why have I explained this? Because, Māluṅkyāputta, it is profitable, it is a starting point for the spiritual life, because it conduces to disenchantment, to dispassion, to cessation, to peace, to higher knowledge, to full awakening, to nirvana; therefore I have explained it. Therefore, Māluṅkyāputta, you should remember what I have not explained as what has not been explained, and remember what I have explained as what has been explained.
In this way, the Buddha explains how Māluṅkyāputta should bear in mind the teachings of suffering (dukkha), its origin and its cessation, and the path to its cessation, as a way of thinking about things; a way that is OK with uncertainty, that bears with what is actually happening, that looks into present experience for the secret of what really matters.
Based on a talk at Cambridge Buddhist Centre on 25 April 2013
 The discourse is no.63 in the Majjhima-Nikāya; its full name is Cūlamāluṅkyaputta-sutta; a full translation by myself can be found at https://dl.dropboxusercontent.com/u/76092054/M%2063%20Short%20Malunkyaputta.pdf, and an alternative translation by Ven. Thanissaro at http://www.accesstoinsight.org/tipitaka/mn/mn.063.than.html.
 This final discourse is found in the Saṃyutta-Nikāya 35:95, and I discuss it in my book This Being, That Becomes, on pp.50–2. The other discourses featuring Māluṅkyāputta are Majjhima-Nikāya 64 and Anguttara-Nikāya 4:254. There are also some verses attributed to him in the Theragāthā.
 The phrase ‘a sentient being’ is a translation of tathāgata, literally, ‘one who has become thus’. While this word usually refers to a Buddha, and is used by Gotama to refer to himself, the commentaries always explain tathāgata in the context of the avyākatāni as satta, ‘creature’, ‘sentient being’, or even as atta, ‘self’. See A Dictionary of Pāli, vol.II, p.286.
 That is, to which among the four varṇas or castes the person belonged.
 It is not certain what some of the Pāli words for these items mean, though the gist is clear enough.
 From a letter to his brothers of 21 December 1817.
 That is, the Buddha has explained the four noble truths.