Nassim Taleb's Black Swan is also a great read on the instability (or in his words, fragility) of knowledge. A single observation is quite often enough to break what has been considered solid knowledge for years.
You can have complete knowledge of a component, but that may not be helpful when attempting to determine the affect of that component in a system where you have incomplete knowledge of other components.
Nonlinear systems that trigger at thresholds are a good example of this.