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In college, I was taught an elegant theory of chemical combination based on excess electrons going into holes in the orbital shell of a neighbouring atom. But what about diatomic compounds like oxygen gas? Don't ask; students aren't ready to know. In physics, in biology, in any other science classes, students frequently get that answer too.

It's time to trust students to handle doubt and diversity in science. Actually, students are starting to act. They have shamed their seniors into including more diverse contributors as faculty members and role models. Young scholars rudely ask their superiors why they fail to address the extinction crises clarified by their research. The inherited authoritarian political structures of science education are becoming lame-but still remain largely unchanged from the old school days.

A narrow, rigid education does not prepare anyone for the complexities of scientific research, applications and policy. If we discourage students from inquiring into the real nature of scientific truths, or exploring how society shapes the questions that researchers ask, how can we prepare them to maintain public trust in science in our "post-truth" world? Diversity and doubt produce creativity; we must make room for them, and stop guiding future scientists into narrow specialties that value technique over thought.

In science, even foundational building blocks can be questioned. The unifying patterns of the periodic table are now questioned under closer examination. Some scientists now wonder whether the concept of biological "species" contributes more confusion than insight, and whether it should therefore be abandoned. However, such a decision, would affect conservation policy, in which identification of endangered species is crucial-so it is not just an issue for basic science.

Science students generally remain unaware that concepts such as elements and species are contested or are even contestable. In school, college and beyond, curricula highlight the technical and hide the reflective. Public arguments among scientists often presume that every problem has just one solution.

Nonetheless, uncertain advice on complex issues should be a warning that, from a future perspective, today's total scientific consensus on some policy issue might have been the result of stubbornness, a conflict of interest or worse. Just as a healthy democracy accommodates dissent and dissonance, the collective consciousness of science would do well to embrace doubt and diversity. This could start with teaching science as a great, flawed, ongoing human achievement, rather than as a collection of cut-and-dried eternal(永久的)truths.

I recall a legendary chemistry professor who was not skillful at getting classroom demonstrations to work-but discussing what went wrong helped his students to thrive. A mathematician friend let pupils discuss every statement in the textbook until all were satisfied. They did very well in exams and taught themselves when he was absent. Treating people at all levels as committed thinkers, whose asking teaches us all, is the key to tackling the challenges to science in the post-trust age.