Here, for the uninitiated, is how real science works:
I flip a switch in front of you and the light turns on. What can you firmly conclude from this? Only that there was what seemed to be a causal relationship between the switch and light. If I repeatedly flip the switch and the light goes off, you can then conclude that flipping the switch has a definite causal relationship with the light going on and off. And that's it.
Why? Because you cannot be sure that the flipping of the switch is what actually turned the light on. Perhaps there's an external factor that notes the switch being flipped and turns on the light. Perhaps I, the flipper, am aware that the light will turn itself on and off and I'm fooling you by timing my switch flipping to a predetermined event that I'm just taking credit for.
In actual fact, it isn't the switch that turns the light on. It's the flow of electrons that is opened up by the flipping of the switch that turns the light on. The switch, which you might have concluded is the direct cause, is actually one step removed from the light turning on.
That's real science.
Here's how skeptics work. We have two Torahs, Jewish and Samaritan, with significant differences between the two texts. The latter is older, the former is known to have been edited over time with final corrections being completed about 1000 years ago, therefore the latter is more authentic. Any changes, being earlier, represent greater authenticity and therefore the differences stand as clear evidence that our Torah was heavily changed over time and thus the seemingly inviolable principle of the unchanging Torah since Sinai is refuted. Not that the skeptics ever believed in Sinai anyway.
How easy is it to tear this thinking apart? Quite easy, using real science. Simply put, the existence of differences between an earlier work of literature and a similar but later one which, at an earlier point in history served as the template for the earlier piece, provides only one legitimate conclusions: there are differences between the two texts.
Who says that because the Samaritan torah is earlier that it is more accurate? One could easily suggest that it's very first edition was corrupted, that most of the differences between our current copy of the Torah and theirs were because of changes that they made, instead of problems creeping into our text. Certainly from a religious perspective this makes tremendous sense. Remember that for those of us who accept that the Written Text was written with the entire Oral Law already in existence and that supposed inconsistencies in the text are intentional clues to allow a reader to derive the Oral Law, it is quite reasonable to note that the Samaritans got their Torah wrong. What for us is a hint to something in the Oral Law would be, to those without that Oral Law, a simple spelling mistake, an incomplete narrative or an inconsistency in the text between one section and another. No wonder their text is different. They were trying to create a more cohesive document from their perspective.
The only way to know which document is more accurate is to find a Torah scroll from the First Temple period from before the destruction of the Northern Kingdom. That Torah would predate both ours and the Samaritan and both could be compared with it to see whose version is more faithful to the original. In the absence of that evidence, one cannot draw conclusions as to whose version is right. It is scientifically unacceptable.
No, we cannot claim that the Torah scrolls we read from today are letter for letter the same as the one given to Moshe Rabeinu, a"h, at Har Sinai. However I have noted before that the point of the Torah is to provide us with an insight into halacha. The Torah we have before us today, with its minor variations from the original , does that in the exact same way as Moshe Rabeinu's did. In other words, it might be just semantics but we do have the same Torah that he received at Har Sinai.