There are core parts of our understanding that would take a lot of counter evidence to really change. For example, evolution. It's as close to a fact as you can possibly get.
On the flip side, there is always fringe parts of science that we are actively generating new models and theories around.
The problem is distinguishing between the two. Yes, you are an idiot if you think the earth is flat. No, you aren't an idiot if you think that we don't have a full understanding of how the brain works.
Scientific "blasphemy" is making a claim with little evidence that runs counter to the current accepted and working models which have mountains of evidence behind them.
It's the "Let's rewrite the whole system" mentality whenever you encounter a small bug in the software. Scientific understanding is generally a bunch of small fixes and tweaks vs rewriting things ever few years.
I just want to add that yes, evolution by natural selection is a mechanism that can help us understand how the natural world came to be as it is. But not entirely. There is also sexual selection for example which leaves species with traits that decrease their pure chances of survival as an individual (think of peacocks dragging along that ridiculous but beautiful tail). And maybe there are more effects, yet undiscovered. I know that group selection is still often a center of debate. I like David Sloan Wilson's work about it [0].
So, yes evolution by several forms of selection is pretty well established but by no means do we fully understand how the natural world came to be as it is today. Which is nice if you ask me.
