I tend to think that it is possible to start undertaking an action while still doubting if one knows that one will soon be certain that what one is undertaking is correct (or not). The degree of certainty and the role of time might be different:
- 1. One might try to add some water to a dough in order to check whether it becomes softer. The result is immediate and doubt is immediately solved.
- 2. One might try to plant some seeds although one does not know whether it is yet too cold for them to grow outside. The result is delayed, but the doubt will sooner or later be solved.
- 3. One might decide to baptize one's baby, although one WILL NEVER KNOW whether this helped her, just because to do it is easy and the alleged risk of not doing it is huge (a baby burning in hell…).
No. 3 somehow resembles Pascal's pari (bet). Its logical possibility rests on the disproportion between the efforts required and the result one might get.
But what about:
- 4. extremely laborious actions whose results will never be experienced in this life?
Would one undertake them while still doubting about their results? Would one, e.g., perform a one-year long sacrifice, give away money, cattle, wealth?
I recall a very interesting discussion about it in Dharmakīrti (concluding that prekṣākārins, people who act in a conscious way, would not undertake such actions without any certainty). Also Mīmāṃsakas claim that trust is needed in regard to the Veda –which cannot be confirmed by any other instrument of knowledge. Hence, in regard to No.4, the problem might be rephrased as follows: How to acquire trust in regard to things one cannot verify?
The discussion about doubt has been raised in some of the last posts. You might wish to check here (Dasti) and here. For a general discussion on doubt, see here. An insightful discussion of Dharmakīrti's case can be found in Vincent Eltschinger's Penser l'Autorité des Écritures, discussed here.