Reason vs Observation
also Rationalism vs Empiricism
The rejection of any forced choice between thinking and observing: both pure rationalism and pure empiricism are mistaken extremes, since reason and observation work together.
A long-standing dispute in epistemology pits rationalism (knowledge comes from pure thinking) against empiricism (knowledge comes from sensory observation). CF treats this as a false alternative: you need not choose. Strong rationalists who try to deduce reality from armchair thinking, and strong empiricists who imagine truth flowing passively into a blank mind, are both wrong. Good thinking integrates the two.
CF’s specific position follows Critical Rationalism on the nature of observation. Observation is never raw or self-interpreting: we must interpret sense data using ideas and background knowledge we already hold, so our observations are as fallible as any other idea. Popper dramatized this by telling an audience to “observe” and waiting until they asked what to observe — we need a goal or conjecture first to direct a targeted search, because there is far more to look at than we can attend to. Observations matter chiefly when they contradict expectations, feeding error correction.
This also marks where CF parts from empiricist justificationism. Evidence does not support or prove theories; there is evidence against ideas but never evidence for them, and induction — deriving theories from accumulated observations — is rejected as a myth. So observation does real work without ever supplying a foundation.
CF notes that Objectivism and Critical Rationalism, despite deep disagreements, converge here: both insist that reason and observation are partners. Knowledge requires active thinking and contact with the world, not one at the expense of the other.