Brown Motion

What is it with someone recommending another someone or sometimes themselves to a certain role or job or relationship?  They start describing the many virtues and the advancements and the accomplishments from the past.  Although past results are no guarantee of future outcomes. We see it in our daily lives - from a good doctor to a skilled plumber to a vesatile restaurant to a good toothbrush.  There are whole businesses that thrive on someone else's ability to recommend something to somebody else. Of course what I find fascinating is not so much that we are inherently a species that likes this social interaction but that we feel compelled to expand on the recommended item or individual beyond what is necessary. If I want a landscaping professional I do not want to ask my friend his opinion only to hear - talk to Renaldo - he is really good.  Why is mere talk to Jose not enough?  Is it because there is some lingering doubt in my friend's mind tha...