You've heard of "kith and kin" but what is kith?

You may think that you form most of your opinions based on logic and careful reasoning, but you'd probably be wrong. One surprising conclusion from my research group's studies of social signaling in everyday situations is that people often let the attitudes and actions of peers, rather than logic or argument, be the dominant guide for their beliefs and actions. It seems that our forebears understood this intuitively and even had a name for it: kith.

While ‘kith and kin' is a thousand-year-old phrase that is still familiar, most of us are at a loss as to the meaning of ‘kith.' The word comes from the old English and old German words for knowledge and it means `a more or less cohesive group with common beliefs and customs.' These are also the roots for `couth,' which means to act with a high degree of sophistication, as well as its more familiar counterpart, ‘uncouth.' Thus, your kith is the circle of peers (not just friends) from whom you learn sophisticated habits of action.

In other words, we are ruled by common sense: the habits our kithmates have in common. This social learning works by modifying our attitudes and beliefs through social influence (usually mediated by social signaling), instead of through critical reasoning.

Need some proof of the impact of kith in modern daily life? Consider the study my colleagues Anmol Madan, David Lazer and I conducted in a university dormitory during the 2008 presidential elections. What we found is that when politics became especially important, as during a presidential debate, the students began to selectively spend face-to-face time with others who shared the same ideological position, excluding those holding differing opinions. This was not true of more remote channels of communication such as phone calls; those remained unchanged, perhaps because they are less effective at conveying social signals.

Further, the extent to which students formed a cohesive `kith' with similar opinions (and presumably fewer political tensions) also predicted their change in political interest, their liberal-conservative balance and even their eventual voting behavior. Amazingly, for first-year students the magnitude of this effect was similar to the effects of political advertising and media exposure. The conclusion is that when people are faced with important decisions they tend to form into cohesive, reinforcing peer groups, providing the social context and reinforcement that will help them shape their opinions and beliefs.


But is it necessarily wise to follow `common' sense - that is, the beliefs of those around you? We have all probably heard the parent-to-teenager admonition of "if all your friends jumped off a cliff, would you jump off too?" And there is an important kernel of truth in that well-worn argument. It is important to understand how social signaling mechanisms can produce intelligent answers, so that we can know when to be guided by our kithmates, and when social signaling mechanisms can lead to poor answers and we need to follow our own path.

About the Authors

Professor Alex "Sandy" Pentland

Alex "Sandy" Pentland has founded more than a dozen companies and social institutions. He directs the MIT Human Dynamics Lab and the Media Lab Entrepreneurship Program.

Tracy Heibeck, Ph.D.

Tracy Heibeck, Ph.D. is a clinical psychologist and award-winning science writer.

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