Gaining support and feedback from people who are similar to us can provide the courage to go on and the motivation to succeed. As such, university departments specializing in science need to be friendly and welcoming to all types of people.
However, young scientists also need to seek and receive often critical feedback from people who are different from themselves. Scientific peer review can be brutal. Young scientists may thus benefit from exposure to diverse types of people and diverse points of view. The conversation about diversity in science often rightly includes motivation to increase the number of students and scientists from underrepresented groups. In some fields, especially physical sciences, women are underrepresented, as are Africans and latinos. In some other fields, men are underrepresented (women with PhDs in psychology outnumber men three to one).
It is not my view that gender parity is needed for the success of science. The free choices of individuals matter to gender balance in different fields. It is difficult to refute the notion that more men like mechanical engineering while more women prefer psychology or medical sciences, even after accounting for effects of any sexism. Regardless of the initial causes of these personal preferences, they really are personal preferences, and I think personal freedom for people to choose to follow their passion is more important than achieving gender balance. The causes of these different preferences could be social, biological, or some combination of the two, and it is not within my expertise to try to explain why, and it does not influence my argument. We cannot force people to choose to do that which does not interest them. Efforts to increase interest of girls (and boys, for that matter) in science are well intentioned but have limited success. When I manage a search committee to fill a job opening, I cannot start with a fifth grader. In my position, I want to include all people who are qualified and who want the job, and I think that where any systemic resistance to inclusion occurs, it should be corrected through positive action, but exclusion is not the only reason for gender disparities.
Even when gender parity is not achieved, scientists may gain advantage by seeking conversations with scientists of the opposite sex and from people from different demographic groups.
Now, don't get me wrong, progress in most of the physical or natural sciences, such as in understanding the nature of a thunderstorm, doesn't require information about whether the scientist is male or female, or black, white, or even purple, for that matter. Any differences between interacting scientists might catalyze opportunities for new insights. Women should thus seek collaboration with men, men with women, and we should all seek interaction with those of other races or ethnicities. I'm not suggesting that every time a male latino scientist has an idea that he should consider it necessary to march down the hall to seek an opinion from an Asian female. Instead, I think that simply having access to and occasionally working with different types of people can enrich the quality of our science overall. Different perspectives don't change the facts, but they might lead us to find previously unrecognized facts and ideas simply by nature of their different experiences. For example, a biologist who grew up in poverty as a farm worker might have insights relevant to the science because she worked in the fields as a youth. For the betterment of science, all types of people from all backgrounds should feel welcome to participate.
The most important interaction we need, though, is with scientists who might disagree with us, regardless of their demographics. This viewpoint diversity is probably the most needed type of diversity for the advancement of science. When there may be multiple views consistent with existing evidence, and perhaps only one or none of them are correct, science can ill afford blanket rejection of viewpoint diversity. Science stagnates when we exclude the perspectives of scientists with points of view that are different from the mainstream. In the end, it is the facts and evidence that lead to a conclusion, not points of view, but different points of view can lead to different ideas of how the facts fit together, and these ideas can mold the direction of the conversation. Occasionally a scientist makes a profound discovery that overturns the mainstream view.
Study of climate change induced by human activities including burning fossil fuels is one field in which some forms of viewpoint diversity are being shut out. I am aware of few climate scientists who argue that increasing carbon dioxide in the atmosphere would not increase the earth's temperature. Nearly every climate scientist agrees that human activities are warming the lower atmosphere, especially in the Arctic (myself included). A large majority of climate scientists agree that more than half of the warming in recent decades is a result of human activities (see the IPCC reports). This type of broad agreement is supported by multiple distinct arguments and analysis techniques. Yet even though the idea of human induced climate change has broad evidential support, the public discourse on this topic is rife with fallacies, especially the argument from authority and argumentum ad populum.
Beyond the points on which most climate scientists agree, there is substantial discussion regarding how much it is likely to warm and how that warming might influence changes in extreme weather events. I think that the most important unanswered questions remaining in climate science relate to how the weather will change with the climate, and how changes in the weather might feed back on the climate. This problem is immensely complicated and the science is still young. People who argue that discussion about climate change and extreme weather events (such as tornadoes, hurricanes, blizzards, and flooding rains) is over or that consensus has been reached on these issues are being dishonest. Scientists are making progress in these areas (such as uncovering evidence suggesting that in many parts of the warming world, both the amount of time between summer rainfall events and the intensity of the rainfall probably will increase), but the problem of the impact of climate change on extreme weather events is far from solved.
Sometimes behaviors of people who fight scientists who express different points of view are similar to behaviors of schoolyard bullies (one such point of view is expressed here). When people argue that "the discussion is over", they shut out conversation where it may be far from over. Some activists and scientists demonize and attempt to exclude from the conversation people who agree that climate change is occurring and is influenced by human activities, but who do not argue that all types of weather are getting worse, or who do not agree on solutions to the problem. These activists often create strawmen descriptions of the contrarian scientists' views in an effort to discredit them.
Rather than address the arguments of scientists who might cast doubt on prevailing views about extreme weather events, detractors label them as deniers or shills for the fossil fuel industry. The ad-hominem attack rears its ugly head. This behavior is inappropriate and unhelpful. Members of the public who remain on the fence on the climate change issue may be turned off by this behavior, and those who do not believe that climate change is occurring may take this behavior of scientists as evidence of a politically motivated conspiracy. Avoiding the appearance of such behavior requires us to patiently discuss errors where we see them, with respect and in light of evidence.
Those opposed to climate change science are often guilty of the same behaviors I describe above, but in the context of the scientific community, the opposite side holds most of the power and needs to be called out. To me both types of negative behavior are reprehensible. Surely we can do better.
