Scottish philosopher Thomas Reid observed in the 1780s that we routinely trust the testimony of our senses without demanding proof — and that this is not naivety but a foundational cognitive move that makes all further thinking possible. Reid called this 'common sense': not folk wisdom, but the set of commitments we have to hold as given before any reasoning can get started. The relevant implication for creative and critical thinking is less obvious than it sounds. Every creative problem you sit with comes pre-loaded with assumptions so basic you're not aware of holding them — about which elements are fixed, which relationships are causal, which outcomes count as solutions. The psychologist Ellen Langer's work on 'conditional learning' shows that when people learn facts as absolute ('this is X') rather than tentative ('this could be X'), they become measurably worse at using that knowledge flexibly when context shifts. Reid gives you the philosophical structure; Langer gives you the mechanism: the assumptions below your reasoning are often older, less examined, and more constraining than anything you'd consciously choose. So the practical move today is specific — not 'question your assumptions' in the abstract, but identify one element of a current problem you've been treating as fixed, and ask what would open up if it were actually a variable.

In a problem you're currently stuck on, what is the one thing you've never once considered changing — not because you decided it was off-limits, but because it didn't occur to you that it could be?

Drawing from Scottish Enlightenment philosophy / Common Sense Realism, synthesized with Langerian social psychology — Thomas Reid (synthesized with Ellen Langer)