How do we know attaining complete liberation from dukkha is possible? How do we know attaining complete liberation from dukkha is possible?
This is a question I’ve made to myself in multiple oportunities, especially after having explained the basics of (what I understand about) the Dhamma to people not acquainted with it. When in such circumstance, I interpret that thought (the question) not necessarily as doubt in the Dhamma, but as a question of “common-sense”.
I have my own arguments that I’ve been buiding over the years about why I think attaining Nibbana is possible, but ultimately, it seems to be just a statement coming from faith and from the extension of a principle that until now has proven to be true, logical, compatible with evidence and useful (namely, the idea of the dukkha as a consequence of tanha, and that the diminishing of the presence of tanha leads to the diminishing of the presence of dukkha).
But, what does assure us that such principle could be applied until the complete eradication of dukkha?
It’s like thinking that just because the scientific method has shown itself to be useful in -apparently- understanding some aspects of reality (based on our ability to use the information gained through the application of the method to predict outcomes, to built technology to achieve some ends, and the ever growing power to keep understanding more and subtler aspects of nature), that would necessarily mean that understanding everything about reality is possible. Personally, I don't think that's the case, because I consider the possibility of reaching a point where our technology does not &quot;expand&quot; enough the power of our senses (i.e., we reach a practical limit of detection of events or presence of some entity or phenomenon), or that there could be stuff in Reality that do not interact with the things we can effectively interact (no matter how subtle or indirect the degree of interaction with such phenomena).
Could it be the case that there is a physical, biological or spiritual (whatever that could mean) condition that could limit the application of the Buddhist method to the very end, just like what could happen with the application of the scientific method?
Just in case, I don’t see any problem admitting to myself that faith in -what the suttas tell us about- the Buddha and in my own experience is what keeps driving me forward in this path. I think that science is not that different in this regard: through inductive reasoning, and assuming the reality of an external world, the possibility of knowledge of (at least) some parts of it, and the regularity of events, faith (or confidence in the reality of the assumptions) seems to be an useful principle when investigating nature.
So, the question can be formulated as such: what is the epistemic justification for having confidence on the possibility of complete eradication of dukkha? One can have confidence, but based, for instance, on this definition of knowledge, how can we justify the belief about the possibility of Nibbana, beyond inductive reasoning and confidence?
I think this question could be particularly beneficial for putting to test the recurring idea of both Buddhism not contradicting knowledge gained (or possible to be eventually gained) through empirical means, and Buddhism as a “science of the mind”.
I’d love to here your thoughts on this.
EDIT: There's an ongoing discussion on this same question of D&amp;D-SuttaCentral. There are very good answers and feedback in my opinion. If you're interested, here you'll find the thread.
Kind regards!
the diminishing of the presence of tanha leads to the diminishing of the presence of dukkha... the extension of this principle... via inductive reasoning... applied all the way until complete eradication of dukkha...

Let's reason logically:
We know that everything in life of a sentient being can be subsumed under subjective experience. For a sentient being subjective experience is life, subjective experience is what matters.
All subjective experience can be broadly categorized as either &quot;rather good&quot; (&quot;nice&quot;, &quot;right&quot;, &quot;satisfying&quot;, &quot;positive&quot;, &quot;pleasant&quot;, or at least acceptable/neutral) or &quot;rather bad&quot; (&quot;nasty&quot;, &quot;wrong&quot;, &quot;annoying&quot;, &quot;negative&quot;, &quot;painful&quot; etc). Therefore, for sentient beings, the character of their subjective experience is the essence of the difference between the Good and the Bad.
Now, subjective experience is made of the mind, it is a state of mind. There's no subjective experience outside of mind. And the nature of mind is representation, it is made of information that stands for something. Therefore subjective experience is a flow of interpretation generating a stream of representations. How can it be good, right, pleasant or bad, wrong, painful?
The nature of interpretation is such that it allows no contradictions. Contradicting evidence interferes with interpretation. Contradicting conclusions are a failure of interpretation. Therefore any such interpretative contradictions are harmful to the very process of interpretation which is the nature of the subjective experience.
Therefore it is the interpretative contradictions that make the difference between the good, right, pleasant, harmonious experience and the bad, wrong, painful, discordant experience.
Now, the interpretative contradictions come from a clash of two or more incompatible representations pertaining to the same subject. The way we give rise to interpretative contradictions is twofold. The coarse ones are created by getting into a circumstance of life with inherent contradiction between the elements of the situation. The subtle ones are generated directly in the mind.
According to the Buddha, the coarse ones are eradicated through the consistent practice of social and behavioral ethics - choosing one's actions such as to not create causes for discordant circumstances - while the remaining subtle ones are eradicated in meditation, by mastering one's attention and interpretation mechanisms as to prevent all kinds of inner discord.
If this were all there was to Buddhism, your doubt would be justified. Indeed, how can we know with absolute certainty that it is possible for an individual sentient being to reach a state where their mind, their process of interpretation, will no longer give rise to any and all interpretative contradictions caused by incompatible representations? Isn't the very nature of mind being a product of representations - simplified and partial by their very nature - inevitably leads to arising of conflicts? Isn't representation inherently conflict-prone?
To answer this question we need to get very clear about the mechanism behind the process of interpretation. Interpretation is an act of translating one or more signs into a category of experience this sign (or signs) signify (or represent). These links between signs and the categories, as well as the signs and the categories themselves, is something we learn from experience and absorb from our parents and other people as well as from various media.
As a sentient being accumulates these signs, categories, and interpretations - it connects them together into one semiconsistent structure called &quot;everything I know about the world&quot;. The same totality of one sentient being's representations, with all its opinions and interpretations is what makes up its personality. Personality is the other side of the coin of &quot;the world as we know it&quot;. The root of personality is Ego, the inferred notion that &quot;I am the subject and my experience is consistent&quot;. In other words, Ego is this assumption that our interpretation and therefore our experience is done from a certain point of view, a certain perspective. 'I am' - thinks the ego - 'therefore my opinions and my actions have an inner logic to them'. The job of ego is endless self-rationalization in order to prove its own existence.
Because ego is all about self-rationalization, it must maintain a semblance of consistency at all cost. Guess what, this dependency on consistency is exactly what makes ego vulnerable to contradicting interpretations! So whenever we have a case of incompatible representations, it is the ego that suffers! It is the ego that is hurt by the conflict! In and off themselves the contradicting interpretations are just that, a logical contradiction. It is hurtful only because we identify with our process of interpretation, we declare ourselves to be the interpreter.
And herein lies the answer to your question. We know the complete liberation from dukkha is possible because we know it is not to be achieved by the process of asymptotic approximation of the conflictless harmonious state. (Although as shown by the Buddha, reducing the outer and inner conflict goes a long way towards achieving the clarity of mind required for the final realization.) Instead, it is achieved by removing the very foundation of conflict - the grasping at a point of view called &quot;I&quot;. When this is done, resulting in the sentient being having no point of view, no position - the representations of the world continue clashing as before, but for the one like this there's no more conflict.
In summary, we don't need mathematical induction too see that complete liberation from dukkha is possible. What's necessary and sufficient is to understand the second noble truth: the arising of dukkha happens due to grasping, the root of grasping is the ego's demand for continuous consistency, therefore letting go of that demand, i.e. letting go of identification with one's knowledge, view, position, perspective, in short, letting go of self-identification - is the final liberation.

the Buddha: Well said, well said! That's right. You have understood it perfectly. You have understood the nature of mind. You are ready to become the next Buddha of this world.
I: Suuuure, and the elephants are actually pink!
the Buddha: That's right. Elephants are actually pink. Everything is pink when you understand the nature of mind.