The curious case of curiosity?

I love a good discussion and on numerous occasions end up playing the role of the devil’s advocate for both sides although I would have set my opinion. It’s simply and nice way to challenge myself as well as others. I do not consider myself an expert in any subject and do not pompously promote such nonsense (I hope that my friends and colleagues attest to this). Nevertheless I strongly believe that curiosity and knowledge is key; How will we extend our understanding of the multitude of concepts and happenings around us.
Then again how do we know that the current fact or analysis is the correct one? I listened to a dear friend a while back arguing a fact because it was scientifically proven. A similar thing happened with a colleague – There was a disagreement on a method of work which was discussed by an expert in the field. Both discussions ended there because these were backed by a quick search on our trusted adviser Google where we found the scientific / expert information.
So in such cases should we not discuss? Because in both scenarios there was either scientific proof or an expert that deliberated the reasoning behind a problem. Just because the latter issues a statement and/or is backed by scientific reasoning is that now complete?
In the book “Brief history of science” by Thomas Crump we see that throughout the ages, science has always evolved, concepts changed, new understanding and findings astonished humankind and although not always towards the right direction we used the knowledge to continue our path to evolution. The same things happened with the great minds and thinkers. Take Charles Darwin and his voyage of the Beagle. He had spent 5 years travelling, collecting samples, classifying organisms and studying extensively before and after his voyage. He would certainly classify as an expert in his field. However, his findings, papers and theory were disputed at the time and still. His book in itself “Origin of species” by Charles Darwin has a number of editions, the theory renamed the same buy further analysis and backing was created for each edition.
Wouldn’t this contradict the questions posed earlier? But then again that would mean that we may question anything and everyone? Based on what happened throughout history should I question all theories and scientific facts? But we already believe what we want to believe. Why is it that in some circumstances we approve a theorem or a scientific fact and in others go to any length to disprove?