Human error cannot be taken out of scientific observation. The world shifts under our gaze, interacting with us, and the knowledge that it yields must be interpreted by us. The scientist who claims that absolute knowledge is attainable opens the door to tragedy. It is important that students bring a certain ragamuffin, barefoot irreverence to their studies. It may be said that a true scientist has an itch for absolute knowledge.
Philosophers have a road to knowledge more perfect than that of observation.
Although we devise ever more precise instruments, we are discomfited to see that our observations are still fuzzy and as uncertain as ever. Scientific methodology, correctly employed, results in unimpeachable conclusions. Whenever instruments of sufficient precision are available, even the finest features of phenomena can be isolated and analyzed. Certainty is achieved through observation, never inference. Physical science has shown that it is the only avenue to knowledge.