Science is considered a self-correcting process because

 If I understand the practice of science correctly, I believe science is so robust because there's no part of it that can't be questioned. Even a small inconsistency could upset a huge theory, forcing everyone to reassess everything they know. 

That's its power. For instance, at the turn of the 20th Century, many (admittedly second-rate) physicists were reportedly complacent that physics had advanced to the point where it might not be possible to improve our understanding of it. 

But there was this small problem that concerned the top physicists at that time. Everyone understood that light was a wave, and not a particle. Experiments had demonstrated wave-like properties of light, so science, apparently, had confirmed this impression. 

However, an inconsistency kept showing up with this picture. It so happened that exposing a metal plate to light that had a lot of blue-color light frequencies in it, would cause that metal plate to emit electrons. (Like solar cells do today - they make electricity.) 

But exposing that plate to light with only red-frequency light "waves," caused no electrons to be emitted - even if very intense red light was used. 

What gives? If energy is transmitted via waves, you'd think at least some electrons would be liberated by light waves. 

This is where Einstein comes in. He demonstrated that light had a particle nature, which particle he named "photons," the term we use to this day. "Red" photons didn't have the energy to kick electrons out of the metal, but "blue" photons did. 

That one observation earned Einstein the Nobel Prize in 1921 (I think), and it led to enormous changes in physics. 

This is why scientists are very, very careful with what they say, and are hyper-critical about the evidence they cite, if they are any good. Over time, this forces the scientific body of knowledge to become more and more powerful at describing phenomena.
Hope this was helpful! (: 

Ok we will i'm sure 456