The relation between Dhamma and reality itself What is the orthodox position or the sutta's position about the knowledge of reality itself, beyond any intervention of subjective factors?

In science, when we find evidence that proves some hypothesis, we cannot say that we've found the truth behind the studied phenomenon. We can only say that, until this point, the hypothesis works and it's useful to explain that phenomenon, and that, until refuted, we can use that hypothesis as a provisional working hypothesis, which is subject to eventual modification. In sum, science help us to find the most useful ideas to use in our lives.

Does this apply to Dhamma as well?

Evidence, (no matter how much evidence, whether theoretical or experiencial) is not enough to posit that the truth has been reached without any posible future refutation. 

Let me ask this with an example:

We can say that the khandhas are not the self, but does that imply that there is not self at all? How can we reach that conclusion without any doubts?

Isn't better to simply say that we cannot know, and that it shouldn't matter at all? After all, if something is beyond the realm of experience, we shouldn't be able to say anything about it.

EDIT: a few more details...

Is Buddhism concerned with ontology (how and what thinfs are by themselves, and not only how we humans perceive them), epistemology (the possiblity of knowing things about reality itself, objectively) or pragmatism (to use whatever seem to work for some specific end)? Is it concerned with all of them, some of them, or none of them?

Pragmatism, for example, doesn't deny the possibility of knowledge, and technology and scientific progress seem to be evidence for that. The problem lies in assuming that this -unknown- degree of certainty is somehow the same as the truth (or the expression of all possible definition or information about a phenomenon). If we arrive to the truth, how could we know? Because of a certain X amount of evidence? How much evidence is indication of reaching the truth?

Or in other words, is enlightenment enough and definitive proof of having reached the truth about reality itself? Does it even matter if it works?

After all, some physicist, in the 19th century, thought that there only a few stuff left to be known about reality, because apparently, there was no important evidence to suggest or indicate that the current theories and hypothesis were wrong nor incomplete. 

Thanks for your time and patience!

Kind regards!
Buddha's Dhamma and the Reality is one thing. Why we are facing problems in this world? And why we are running after different things? 

It is because we haven't understood the reality of the world. 

Different people run after different things (Youngers -&gt; Money, Politicians -&gt; Power, Who-does't-have-water-to-drink -&gt; Water, Mother -&gt; Children, Students -&gt; Knowledge, etc...) They all has one thing in their mind, that is they will get satisfied after they achieved their goal. If you ask from an old person has he/she achieved their goals, they will replying saying Yes, But then if you ask them whether they are Satisfied. They will think twice to answer. Because What they really ran after was, Satisfaction, or Ultimate Satisfaction But they couldn't find the ultimate satisfaction on any of their goals.

(Note: If you are ultimately satisfied of something you don't want to do it any more and you should have the happiness in your mind about it. Isn't it?)

Why? Why they couldn't get satisfied? Because They don't know where they should look for ultimate satisfaction which gives them the ultimate happiness. Then where's that place which will make someone happy forever. Which will make someone stress-free, suffer-free.

Buddha's teaching is to teach us where that ultimate satisfaction / happiness is. If you understand the problem of the world, which I mentioned above, according to the science you will identify there's a problem. And If you follow the path of Buddha you will see that how it can be solved. Basically when you are following the path you will see why we are not satisfied with this world and what's the reason for that. And how the ultimate happiness feels like.

If I answer to the example you gave;


  We can say that the khandhas are not the self, but does that imply
  that there is not self at all? How can we reach that conclusion
  without any doubts?


You can't reach there because that's not the correct Dhamma. In Canon, Cūḷavedalla Sutta  Sakkaya is defined as below. (Please replace the word identity with Sakkaya and read the below) And you will understand that Sakkaya has nothing to do with Self or Identity. These translations doesn't give the exact meaning of Buddha's teaching.


  “Ma’am, they speak of this thing called identity. What is this
  identity that the Buddha spoke of?”
  
  “Visākha, the Buddha said that these five grasping aggregates are
  identity. That is: form, feeling, perception, choices, and
  consciousness. The Buddha said that these five grasping aggregates are
  identity.”


So instead of trying to conclude with there is not self at all Find Buddha's meaning of Sakkaya Ditti. Because that's the entrance to Buddha's Dhamma.

Update - 1
Based on the comment below part is added. It's hard to say Yes, No as Buddhism is towards the Nivana = Englightment.


Epistemology (Epistemology is the study of the nature of knowledge, justification, and the rationality of belief.) : Yes, Buddhism concerned about this. Because We don't understand the nature of knowledge, justification, and the rationality of belief that's why we are in suffering. The Buddha studied this and understand the nature of how we think towards above factors, and that made him realized the root cause for this Sansara journey.
Ontology (Ontology is the philosophical study of being) : Buddhism explains the existence of the world, the reality of the world, and how beings are related. The main thing Buddhism focus is the reality of the world. While getting there how things are related to each other and how/why that exist are also get explained.
Pragmatism (An approach that evaluates theories or beliefs in terms of the success of their practical application) : In the path to Nivana he / she can evaluate which makes him/her success. Because how Buddha has advised is it's up to us to follow the path getting advises from the teacher which is Dhamma not a person.