Answer: Fallibility.
Acknowledging the scientific principle of fallibility means that the researcher is aware that science is a growing body of information. While everyone who contributes to it try their best to be rigorous, conclusions can sometimes be mistakes.
Sometimes this is because of some inherent shortcoming in the method. It can also be due to some oversight of the researchers, or lack of data. Sometimes it is simply that we have new information we did not have before, therefore we can make conclusions we could not have made before.
It is important for a researcher to be aware that, while it is fine to be proud and confident on your work, one should always be open to the possibility of being proven wrong as more information surfaces.