Think Like a Scientist
Treat your beliefs as hypotheses and your decisions as experiments
The foundational framework of Think Again. Grant argues that most people default to three mental modes when forming opinions: preacher (promoting ideals), prosecutor (proving others wrong), or politician (seeking approval). The scientist mode is the antidote, where you search for truth by running experiments and testing hypotheses.
In a study of Italian startup founders, those trained to think like scientists brought in revenue more than twice as fast as a control group. The difference was that scientific thinkers pivoted more than twice as often when their hypotheses were not supported, while the control group stayed wedded to their original strategies.
The core practice is to approach every belief, strategy, and opinion as a provisional hypothesis rather than a settled truth. You actively seek disconfirming evidence, design tests for your assumptions, and update your views based on data rather than ego. This does not mean being indecisive; it means being decisively open to revision.
- Treat every opinion as a hypothesis to be tested, not a truth to be defended
- Seek disconfirming evidence as actively as you seek confirming evidence
- Measure results rigorously and let data drive decisions about pivoting or persevering
- Maintain the agility to update your views when your experiments produce unexpected results
- Separate your identity from your ideas so that changing your mind feels like growth, not loss
- Identify your current hypothesesWrite down your key beliefs, strategies, or opinions on a given topic. Reframe each one explicitly as a hypothesis rather than a fact. For example, change 'Our customers want feature X' to 'We hypothesize that customers want feature X.'
- Design falsifiable testsFor each hypothesis, determine what evidence would prove it wrong. Create a small, low-cost experiment that could generate that evidence. Define your success and failure criteria in advance so you cannot rationalize unexpected results.
- Run the experiment and collect dataExecute your test and gather results without confirmation bias. Record both supporting and contradicting evidence. Seek feedback from people who are likely to disagree with your hypothesis.
- Update or pivot based on resultsIf your hypothesis is supported, proceed with increased but still provisional confidence. If refuted, treat it as a discovery rather than a failure. Revise your hypothesis and design the next experiment. The Italian entrepreneurs who succeeded pivoted more than twice as often as those who failed.
Mike Lazaridis created the BlackBerry and dominated nearly half the U.S. smartphone market by 2009. When the iPhone launched, he dismissed the touchscreen keyboard and resisted adding features beyond corporate email. He stayed in preacher mode about his product's superiority rather than testing his assumptions against the changing market.
Over a hundred Italian startup founders were randomly assigned to either a scientific thinking training or a control group. Both received identical entrepreneurship training, except the scientific group was taught to view strategies as theories, customer interviews as hypothesis development, and prototypes as experiments. They were trained to rigorously measure results and pivot based on evidence.
Grant opens the book with the story of Mike Lazaridis, creator of the BlackBerry. Lazaridis had the spark that ignited the smartphone revolution, but his struggles with rethinking destroyed his company. He dismissed the iPhone's touchscreen keyboard and resisted adding a browser or email capability beyond corporate networks. Grant contrasts this with a study of Italian entrepreneurs in Milan, where those randomly assigned to view their startup strategies as scientific experiments dramatically outperformed their peers, earning over $12,000 in average revenue versus under $300 for the control group.