I recently read Clear Thinking during a half-term break in Somerset, away from the noise of Shanghai and the constant low-grade chaos of a school term. I'd intended to read fiction. Something about the title drew me in — probably the promise of order, which is what every teacher craves after six weeks of managing thirty personalities at once. What I found was less a manual than a mirror. Parrish doesn't just describe clear thinking; he shows you, uncomfortably clearly, how rarely you practise it.
Parrish argues that clear thinking isn't a personality trait but a skill that can be trained. He focuses on what he calls "defaults" — the emotional, ego-driven, social patterns that hijack our cognition before we even realise we're thinking. The book is a guide to recognising these defaults and building systems that protect you from them. It draws heavily on psychology, military strategy, and Parrish's own experience running the popular blog Farnam Street.
The concept that stayed with me was "decision rules" — pre-commitments you make when you're calm that govern your behaviour when you're not. I've started using a version of this in my teaching. Before the term starts, I decide which behaviours I'll always challenge and which I'll let go. Without that clarity, I react inconsistently, and the students suffer for it. It's a small change, but it's made me a calmer and more effective teacher.
Parrish is also excellent on how ego distorts judgment. The need to be right. The fear of looking stupid. The tendency to defend a position because it's yours, not because it's correct. In local government, I watched meetings drag on for hours because no one was willing to abandon a proposal they'd already publicly supported. The cost of ego was measured in wasted time and worse policy.
Some people say that decision-making books are just common sense dressed up in frameworks, and that no one actually changes how they think after reading them. There's some truth to this — most business books are read and forgotten within a month. But Parrish's approach is more structural than most. He's not asking you to try harder. He's asking you to build better systems. That distinction matters. Willpower is unreliable. Rules are not. Living in China has made this even clearer to me. The pace of life here is relentless, and the default mode is reaction. Someone sends a WeChat message; you reply immediately. A parent complains; you apologise and adjust. Parrish would call this "urgency hijacking" — the tendency to let the loudest input determine your attention. Breaking that pattern requires structure, not willpower.
This isn't a comfortable read. It'll make you aware of how often you're on autopilot. But awareness is the first step toward change, and change — real, sustained change in how you make decisions — is worth the discomfort. If you want to think more clearly, start with the defaults. You can't fix your thinking until you know what's broken. Build your rules before you need them. The moment of crisis is the wrong time to decide how you'll behave. And accept that you'll still fail. Clear thinking isn't a state you achieve. It's a practice you maintain. Expect to slip.