How to let go of doubt?

A. Nourishment of Doubt

There are things causing doubt; frequently giving unwise attention to them — that is the nourishment for the arising of doubt that has not yet arisen, and for the increase and strengthening of doubt that has already arisen.— SN 46:51

B. Denourishing of Doubt

There are things which are wholesome or unwholesome, blameless or blameworthy, noble or low, and (other) contrasts of dark and bright; frequently giving wise attention to them — that is the denourishing of the arising of doubt that has not yet arisen, and of the increase and strengthening of doubt that has already arisen.

These six things according to the commentary are conducive to the abandonment of doubt;

• 1. Knowledge and pondering of the Dhamma;
• 2. Asking questions about the Dhamma;
• 3. Familiarity with the Vinaya (the Code of Monastic Discipline, and for lay followers, with the principles of moral conduct);
• 4. Firm conviction concerning the Buddha, Dhamma and Sangha.
• 5. Noble friendship;
• 6. Suitable conversation.

In addition, the following are helpful in conquering Doubt:

• Reflection, of the factors of absorption (jhananga);
• Wisdom, of the spiritual faculties (indriya);
• Investigation of Dhamma, of the factors of enlightenment (bojjhanga).

C. Simile

If there is a pot of water which is turbid, stirred up and muddy, and this pot is put into a dark place, then a man with a normal faculty of sight could not properly recognize and see the image of his own face. In the same way, when one's mind is possessed by doubt, overpowered by doubt, then one cannot properly see the escape from doubt which has arisen; then one does not properly understand one's own welfare, nor that of another, nor that of both; and also texts memorized a long time ago do not come into one's mind, not to speak of those not memorized — SN 46:55

These are sutta and commentary take on this.

In general i think learning, pondering and understanding is most helpful in overcoming doubt.

It is also very important not to dwell on it too much because if you give it attention it becomes the inclination of mind.

One can set some doubts aside if it's not immediately pressing, thinking; 'Now i have doubts, what use is dwelling on these now; what can i now do about these doubts? Why don't i set these doubts aside for now and figure it out later?"

Alternatively you can go trying to figure it out there and then if there is an opening

You can also for the time being think; 'Certainly i am unsure about the truth, in order to protect the truth, why don't i hold the view that "maybe it is like this or maybe it is like that or maybe it is somehow otherwise" and set this issue aside for now and later investigate the matter further?'

This might help to set it aside.

Good householder,

doubt (in regard of the path, the Gems, Nibbana, that escape is possible) actually ends only by entering the stream, by having seen for oneself. Till then doubt will be ones attendant.

So for the whole practice Saddha, confidence, faith, is most necessary. The transcendent depending co-arising, pointed out by the Sublime Buddha, gives Dukkha (suffering, stress) as cause for the arising of Saddha. So if one has heard the Dhamma of the Arahats - knows that the six senses, there objects, what ever arises on touch on them, are not real, insecure, subject of change, no refuge, not worthy to regard them as mine, me - does well to always keep that in mind and let fear in regard of the world not fade, nourishes, next to Saddha, Samvega.

Conditions and detail points to nurish a urgency and doubt in regard of the world are already given in other answers (see Upasaka Maga2020 answer), dealing with the fetter in- and of itself.

So generally the way to increase Saddha and cut off doubt is lesser a matter of desire for certain happiness at first place, but to face Dukkha to gain a drive. The lesser ways to seek after other kinds of happiness in the world, the five senses, the more certain (reminded onthe good Dhamma) that one get's fuller aware of suffering and as the original word of Saddhā derives form Saddh(a), sacrificing, giving, letting go, beginns to let go of the causes, the world, the senses. Having now an escape known, if reminded, the entering of the stream can be quick, very quick, and with it douts are abounded. They may still temporary arise but can no more lead to real bad action, kamma.

Outwardly, like always in this heritage heard, is there nothing more conductive then association with wise, real 'friend' and to withdraw more and more from 'bad' friend, lower or equal in virtues.

May good householder therefore find, after seeking wisely, be/do always near association with the wise. May he not go after, seek, after fools, especially doubtful natures, avoiding them like a sickness's cause.

[Note that this isn't given for stacks, exchang, what ever other world-binding trade, but for release from dout, for ones key to escape]

Following reasons might create doubt in your mind :
1.Mara is evil and will cheat you. Mara will offer you everything you ever wanted. Mara will make you doubt the Dhamma. You will have to save yourself from going on the evil path.
2.If you have doubt over Dhamma then probably you are attached to family , possessions, money etc ... The pain of leaving all that makes you doubt the Dhamma.
3. You have not understood Dhamma which speaks nothing but Truth. Truth which can not hidden for long that the world is unsatisfactory.
4. You have not experienced suffering because it was deliberately hidden from you.
5. You do not have faith in Buddha who is the teacher of Gods.

Meditate as told in Suttas. Meditation will help you concentrate your mind with right view.A concentrated mind is more capable of seeing the obvious Truth. If you practice mindfulness I think you will understand what Buddha was talking about. Once you have understood that this is suffering ,your doubts will vanish automatically.

I personally have no doubt because I have experienced suffering.

@Danyaal, your statement:

My mind is unfortunately very logically driven.

points to a way forward. Suppressing your doubts about meditation will not accomplish anything other than retarding your progress. Being logically driven is not a deficiency in Buddhism, except to those who confuse conceptual thinking for logic. All you have to do is read any sutra to see the depth of logic involved in Buddhism. The key is seeing how that logic is applied. And this leads the way to not only evaporating your doubts, but also, learning the distinction between conceptual thoughts (name and form), which forever obfuscate the truth from you, and logical analysis that undermines the cause of doubts, when it is properly applied.

To that end, meditating on the specific doubts that you have, and then analyzing their origin and the justifications that you have been inculcated with as to their validity is a good way to proceed.

You say that you need proper proof before you apply your full energy to the path of meditation, but I am suggesting that what you need to do is disprove the ideas and preconceived notions that lead you to doubt the usefulness or efficacy of what you are doing.

As you are working on your concentration, via the breath, you will find some benefit to noticing when these doubts arise, whether meditating or not, and when you notice them, look into which particular notion you have that causes you to doubt. Once you identify that, you can then analyze (on or off the mat) that notion.

Initially, you may want to refer to sutras or other writings that may help. I myself am very analytically oriented, and having started meditating at a young age, found myself confronted by experiences that did not fit the views of my school teachers, parents, and friends, and I was severely blocked by this. It was only after I realized that I should instead try to fit what I was being taught into what I was experiencing in meditation that I could make progress in my life, and along my path.

I have written many articles that detail how I managed to break-free of the conceptual illusions that I was taught, fitting them into a clearer understanding that was coming out of my practice. These can be of benefit to someone who requires this kind of analysis—seeing for yourself whether they are true, or just assumptions that create doubt, and sometimes, distaste towards meditation. I don’t want to post links, which might be a violation of protocol here, as I am new to this site. But if you would like links to the material (published on Medium) please send me a message.

I hope you find this useful.

Just a short epilogue to my answer: when the Buddha taught, his words were directed to the context and individuals present. Thus we received his so-called 84,000 teachings, always varying slightly. But today our context is different in one significant way: modern science and it’s practitioners who have convinced us all that their imaginative interpretations (because all interpretations of realty are imaginative) are true and correct. Thus we are inculcated with stories about how things work, and how things truly are from these authorities, and accept them as we interpret what they are saying. This is why we need to analyze them ourselves to see if what we think is meant is correct, and if what science holds to be true is so. It is through this process we can dispel doubts.

Doubt:

Why do I age? Why do I fall into disease? Why do I encounter sorrow? Why do I encounter suffering?

Clarification: Because I was born. When there is birth, there is suffering decay and death. When birth occurs, with it occurs suffering, decay and death.

Doubt:

Why was I born?

In this manner, one can and should contemplate paticca samuppada. That is a wise place to doubt and clarify.

You can also read Kalama Sutta and find a set of villagers who had doubt and asked lord buddha what to do.

In Buddhism there is no unrooted faith. There is only logical (methodical or in accordance) faith. Most other followings except science follow unrooted faith (no logic behind it).

To that effect, you can find more in Chula Hatthi Padopama Sutta, about a man who worships Buddha merely by hearing a few good things about him.

There is also a Sutta which a man speaks to Buddha that people are impressed about his virtues and Buddha states that should not be the reason to have faith in him. I don't remember its name.

If assailed by doubt during meditation, the solution is to first receive clear instructions for meditation, then later during meditation, to let go and have complete trust in the process.

Please see the section on doubt from the essay "The Five Hindrances" by Ven. Ajahn Brahm:

Doubt refers to the disturbing inner questions at a time when one should be silently moving deeper. Doubt can question one's own ability "Can I do This?", or question the method "Is this the right way?", or even question the meaning "What is this?". It should be remembered that such questions are obstacles to meditation because they are asked at the wrong time and thus become an intrusion, obscuring one's clarity.

The Lord Buddha likened doubt to being lost in a desert, not recognising any landmarks.

Such doubt is overcome by gathering clear instructions, having a good map, so that one can recognise the subtle landmarks in the unfamiliar territory of deep meditation and so know which way to go. Doubt in one's ability is overcome by nurturing self confidence with a good teacher. A meditation teacher is like a coach who convinces the sports team that they can succeed. The Lord Buddha stated that one can, one will, reach Jhana and Enlightenment if one carefully and patiently follows the instructions. The only uncertainty is 'when'! Experience also overcomes doubt about one's ability and also doubt whether this is the right path. As one realised for oneself the beautiful stages of the path, one discovers that one is indeed capable of the very highest, and that this is the path that leads one there.

The doubt that takes the form of constant assessing "Is this Jhana?" "How am I going?", is overcome by realising that such questions are best left to the end, to the final couple of minutes of the meditation. A jury only makes its judgement at the end of the trial, when all the evidence has been presented. Similarly, a skilful meditator pursues a silent gathering of evidence, reviewing it only at the end to uncover its meaning.

The end of doubt, in meditation, is described by a mind which has full trust in the silence, and so doesn't interfere with any inner speech. Like having a good chauffeur, one sits silently on the journey out of trust in the driver.