Reconciling the Fermi Paradox

Synopsis

 Statistical averages like the Drake equation attempt to derive an expectation value for the number of alien civilizations in the universe out of an enormous and uncertain parameter space. Inevitably, no matter how unlikely we posit intelligent life to be, it turns out we should still expect to see many intelligent civilizations cohabiting our universe. That we have not yet observed extraterrestrial intelligence is a vexatious and interesting problem called the Fermi Paradox. 

Is the paradox because we don't understand the origin of life very well? That we have only observed a tiny fraction of the universe? Or maybe do we need to think more deeply about the statistical implications of the Drake Equation?