The scientific attitude prepares us to think smarter. Smart thinking, called critical thinking, examines assumptions, appraises the source, discerns hidden values, evaluates evidence, and assesses conclusions. Whether reading online commentary or listening to a conversation, critical thinkers ask questions: How do they know that? What is this person’s agenda? Is the conclusion based on anecdote and gut feelings, or on evidence? Does the evidence justify a cause–effect conclusion? What alternative explanations are possible?

Critical thinking, informed by science, helps clear the colored lenses of our biases. Consider: Does climate change threaten our future, and, if so, is it human-caused? In 2009, climate-action advocates interpreted an Australian heat wave and dust storms as evidence of climate change. In 2010, climate-change skeptics perceived North American bitter cold and East Coast blizzards as discounting global warming. Rather than having their understanding of climate change swayed by today’s weather, or by their own political views, critical thinkers say, “Show me the evidence.” Over time, is the Earth actually warming? Are the polar ice caps melting? Are vegetation patterns changing? And is human activity spewing gases that would lead us to expect such changes? When contemplating such issues, critical thinkers will consider the credibility of sources. They will look at the evidence (Do the facts support them, or are they just makin’ stuff up?). They will recognize multiple perspectives. And they will expose themselves to news sources that challenge their preconceived ideas.

Has psychology’s critical inquiry been open to surprising findings? The answer, as ensuing modules illustrate, is plainly Yes. Some examples: Massive losses of brain tissue early in life may actually have minimal long-term effects. Within days, newborns can recognize their mother by her odor. After brain damage, a person may be able to learn new skills yet be completely unaware of such learning. Diverse groups—men and women, old and young, rich and middle class, those with disabilities and those without—report roughly comparable levels of personal happiness.

25

And has critical inquiry convincingly debunked popular presumptions? The answer, as ensuing modules also illustrate, is again Yes. Research shows that sleep-walkers are not acting out their dreams. Our past experiences are not all recorded verbatim in our brains; with brain stimulation or hypnosis, one cannot simply “hit the replay button” and relive long-buried or repressed memories. Most people do not suffer from low self-esteem, and high self-esteem is not all good. Opposites do not generally attract. In each of these instances and more, what scientists have learned is not what is widely believed.

Psychological science can also identify effective policies. To deter crime, should we invest money in lengthening prison sentences or increase the likelihood of arrest? To help people recover from a trauma, should counselors help them relive it, or not? To increase voting, should we tell people about the low turnout problem, or emphasize that their peers are voting? When put to critical thinking’s test—and contrary to common practice—the second option in each case wins (Shafir, 2013).