A growing number of concerned parents have gotten wind of rumors that vaccines may lead to brain damage in their young children. Even after the evidence behind this claim has been invalidated by medical experts, it continues to challenge the credibility of science and increase the risk of disease epidemics for everyone in society.We live in a world filled with myths, urban legends, ideological beliefs, and strong opinions that present themselves as expertise. We also live in a world filled with complex problems that can only be solved through highly specific scientific knowledge. This poses a great challenge for humanity. How do we discern credible knowledge in a myth-filled world?Two examples show just how acute the problems are:1) Planetary Climate is Changing and the world is divided into camps based on strongly held opinions, moral judgments, and ideological beliefs. While few people dispute the fact that extreme weather is causing all sorts of problems, many still cling to ideas that match their worldview and confuse others around them about what is really going on. The public debate about climate science rages on more than a decade after the scientific community resolved the issues and clearly found that human activities are disrupting planetary climate,2) Health Concerns Arise Dailyand people select medical information that conforms to their individual sensibilities — some people opting to scour the peer-review literature for information they can trust while others jump on the bandwagon of nutritional fads and urban myths about vaccines, herbal remedies, and naturopathic medicine. How can they tell what will actually work best? In today’s world of ready access to information on the internet, an increasing number of people are taking medical diagnosis into their own hands—especially when they disagree with the prescriptions from their doctors, whose credibility is increasingly called into question.I have grappled with these issues quite a lot over the last decade. The approach I took was to study human cognition and the various ways that our minds shape what we perceive and how we act upon in the world. This has been informed by linguistics (how information processing in the brain shapes how we make sense of the world); psychology (the role of emotions in shaping whom we trust and how we evaluate information presented to us); anthropology (evolutionary and tribal origins of social morality that influence how we build trust in group settings); and other research areas that are relevant to this topic.As editor at TVOL, I make a point to move beyond my own perspectives — realizing from all the study mentioned above just how limited and unreliable one person’s view can be, no matter how well informed one tries to be. In my attempts to overcome these cognitive shortcomings, I try to seek advice from people whose expertise differs from my own. I recently interviewed Professor Harry Collins at Cardiff University about his research in the sociology of science to learn about the many kinds of expertise that have been discovered over the years.Harry Collins recommends that everyone working to address complex technical problems should learn more about what sociology has to say about science. A great deal is now known about the social norms that shape group decisions. Quite a lot is known regarding the importance of status and reputation in any community of practice, scientists included. In his own work, Collins has followed the research practices of physicists studying gravitational waves — a topic that is so profoundly shaped by theory and instrumentation that even those close to the work have great difficulty discerning what is real and knowable. Thus it is an excellent place for a sociologist to go and observe how groups of people argue, collaborate, and make progress (or not) as a social dynamic filled with intricacies and nuance.My introduction to Collins’ work was his recent book, Are We All Scientific Experts Now?, an easy read for laypeople and researchers alike to learn about the different kinds of expertise that exist in the world. There are many things I could say about this book. For the sake of brevity, I will focus on what I feel is one of the most important insights explored within its pages. There are many different kinds of expertise. Most of it is not learned from reading books or peer-reviewed papers. Most of what scientists learn about their field does not come from experiments. They learn it by attending lectures, participating in conferences, and so forth — in a word, they learn it from other scientists.This is important for our discussion in a very specific way. The only way to know what knowledge is trustworthy is to observe what the experts WITHIN the community of practice discern to be trustworthy. Reading popular science books on the topic is not enough. Even reading peer-review journal articles is not enough. Only those people “in the know” about which research is widely cited and built upon can say with authority what the state of the field is.Why is this the case? Because some researchers have little credibility with their peers. Those researchers are still able to get their work published in peer-review journals. But no one in the community reads them! This is because the type of expertise at play is local knowledge of reputation and status within the scientific field itself. Without this knowledge to guide you, it is very easy to be led astray. This kind of social trust is like a glue in human communities.Evolutionary research on the origins of human sociality shows that reputation and status are managed by the spread of gossip, commentaries about the moral worth of different people, and—in particular—whether they are trustworthy and credible. In his book Grooming, Gossip, and the Evolution of Language, Robin Dunbar explores this topic at length. Among his key assertions is that “social grooming” among peers is a vital form of communication that helps members of a community know who is credible and who is not in situations where there are more people than each can know personally.Let’s apply this to the examples mentioned at the beginning of this article, climate change and medicine. It is quite easy to have an opinion about these topics before starting to search for information. In subtle (and sometimes overt) ways, this opinion can shape how you search for information, which articles you read, and to whom you turn for expert opinion. Every step of the way, you are influenced by your level of trust in some sources over others. You may ultimately come to a conclusion after your “research” into the field — but you never spoke with a practicing scientist with vital social knowledge about the credibility of their peers. And so you would not easily know if the sources you looked at, even those in scientific journals, should be taken seriously.This is different from the problem of cheaters or people who “cook the books” to produce fake results. Collins is referring to those people who do research deemed sufficient in quality to warrant publication, yet are not considered credible enough to draw attention from other researchers in the same field. In this sense it is a more difficult problem to overcome. The cranks and charlatans are easier to spot. Those who explore topics that have been discredited by the community, yet do so with some degree of rigor, are only going to be known as “unworthy” by others with sufficient technical and social knowledge within the research community.This is a sociological problem and it has a sociological solution. Learn how credibility and expertise work in social systems (in other words, study the sociology of science) and apply what they have learned to your own learning process. If you want to know what the state of knowledge is for climate change, attend a major conference of climate scientists and ask them about the major ideas they consider trustworthy. Do this and you will get a lot farther along than reading articles and books on your own.The same lesson applies to medicine and public health, evolutionary studies about human nature and group behavior, engineering solutions for energy and food supply, policy interventions that address poverty and inequality, or any other problem whose solutions can be informed by technical knowledge.Applying this to the concern about vaccinations mentioned at the beginning of this article, if you want to know what is really going on it is best to consult the researchers themselves. Go to one of their gatherings (or read an official statement by one of their respected professional associations) and ask around. Do this and you will quickly learn that the lone study that kicked the entire controversy off all those years ago has since been found to have faulty data. It has been cast out by the community and lacks credibility.In our ongoing quest to solve the big problems in the world, we will need to keep learning about the sociology of science to ensure that we find credible knowledge. This is one small piece of the larger web of challenges in our media saturated world.