Pascal vs. the Buddha

Pascal’s Wager is sometimes said to be the first formal use of decision theory. Blaise Pascal of the 17th century reasoned thus: if one believes in the Christian God

  • and the belief turns out correct, one is rewarded with an eternity of gain (or, conversely, avoids an eternity in hell);
  • if the belief is wrong, one loses almost nothing.

The thought struck me that the lesser known second part of the Kalama Sutta is also a similar application of decision theory. This is about 2,200 years earlier than Pascal. But it was not as formally laid out, and is also a far more complicated (but therefore more realistic) case.

The Buddha applied it to moral decisions in the context of the extent to which one believes in the cause and effect of one’s actions, or simply put, Kamma/Karma, the full extent of which is necessarily linked to rebirth.

Although how causes, moderated by conditions, lead to their effects is a highly complex matter, they are generally still apparent to us (think physics) and therefore believable… except for the catch that there might not be enough time for all effects to come to fruition within one lifetime. Therefore rebirth completes the idea of Karma by providing opportunity in the future for fruition of effects.

Ordinary people, however, do not have knowledge of their past lives or that of others’, so the idea of rebirth is not as apparent and believable.

According to the Buddha’s reasoning as re-told by the Kalama Sutta, if one acted accordingly to avoid unwholesome deeds and carry out wholesome ones throughout this life:

  • if rebirth were true, one benefits in this life as well as after the end of this life by having a better rebirth;
  • if rebirth were not true, one most probably still benefits by having lived blamelessly and avoided substantial suffering in this life.

I did a quick Google and found out that other people have linked this to Pascal’s Wager before. In fact, some folks online called this the Buddha’s Wager. There is also another scripture that is in the same spirit: the Apannaka Sutta.

The Buddha’s Wager is a far more complex application of decision theory, however, because:

  1. Pay-offs is positive (according to the formulation above; just like Pascal’s Wager, it can be formulated in the negative sense, i.e., living an unwholesome life) in both options, just that one (with afterlife) is on top of the other (this life only). In Pascal’s case, pay-off is usually taken as neutral (=zero) in the worse of the options (but see below).
  2. The degree of uncertainty is different between the two pay-offs. It seems to me that this is a critical part of the Buddha’s version. Cause and effect within this life is more believable (=lower uncertainty) because it is usually observable; rebirth (i.e., continuation of cause and effect after death) on the other hand is usually not observable and therefore highly uncertain. (In Pascal’s case, there is only one non-zero pay-off option so uncertainty is only relevant for that pay-off.)
  3. There is a cost involved, because this case, in contrast to Pascal’s in the context of Christian doctrine, is not just about belief but about taking action. Acting incurs opportunity cost in the process, e.g., effort invested, or “opportunities” missed from not taking advantage of others or not indulging oneself.

The Buddha’s case is therefore pitting a additional pay-out (P1) that has higher uncertainty (U1) together with a basic pay-out (P2) that has lower uncertainty (U2) against the cost of action (C). So one should only take action and incur the cost if one can be sure that the combined expected benefits are high enough:

P1* (1-U1)+ P2* (1-U2) – C > 0

The Buddha’s Wager is not so much of a wager as it is a statement of inequality: that P2* (1-U2) > C so that the value of U1 is irrelevant, i.e., the benefits of a wholesome life are sufficient in itself to justify us taking the trouble, whether or not there is an afterlife. In such a formulation, the Buddha portrays moral behaviour as cost-beneficial regardless of afterlife belief.

If we go strictly by the Kalama Sutta, U2 seems to be taken to be zero, which reduces the inequality condition to an even simpler one: P2 C. Herein lies the link back to the rest of the Kalama Sutta, and the difference between Pascal’s Wager and the Buddha’s version.

In Pascal’s Wager, the pay-off in choosing to believe is positive infinite. In such a system, nothing finite can be greater than positive infinite, so the pay-off for disbelief, even if positive and not zero, will never outweigh the pay-off for belief. This means that Pascal’s Wager, while logical, is still a non-falsifiable statement of theistic belief.

On the other hand, the Buddha’s inequality statement is possible to be false, and therefore can be subjected to testing; one just needs to estimate P2 and C. This is why it fits in with the first half of the Kalama Sutta: the Buddha’s exhortation to the Kalamas not to base their actions on the sole basis of belief, but to test it out for themselves and weigh the benefits and costs of their actions for themselves and others.

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