What Makes an Expert

I just returned from some presentations I did in Winnipeg, Manitoba, and at the conference I was introduced as an "expert" in the concept of social capital.  I did my presentation but later reflected on the introduction and it caused me to think about what makes an expert.  Indeed, I have done advanced study on the notion of community and social capital, as well as having garnered actual experience in the work we do at CLASS - but does this make me an expert in the subject?

Certainly we are exposed to experts all the time; we see and hear them in the media speaking about things they are supposed to know more about than the average person.  When we go to conferences or events, experts are on the program to discuss subjects in which they have some expertise.  So, what makes someone an expert?

To me, expertise is a combination of a number of factors.  Of course, we expect that an expert has some advanced knowledge, study, or familiarity with the topic.  I want them to have some formal, rigorous efforts in the topic via study, research, or deep exposure.  I would also want them to have some direct experience with the topic and not just understand it academically, but to have wrestled with it in application.  Last, I hope the expert has some broader wisdom and can understand the direct application of the subject in everyday life.

In this day of social media and open access to other people, we really need to be cautious about who we believe.  Thinking about a topic, and then putting trust in what the "expert" says about it can make any life application easier, or harder; so we should really think about the credentials the expert has in the subject. 

So what do you think - what makes an expert in your opinion?  Who do you tend to believe on subjects, and why?