Okay, we have come to know that sincerity itself is valuable. It cannot be traded for personal interest. This is to say we trade sincerity for more utility. But it is quite difficult to maintain sincerity, because if people, the great people, believe that a lie somehow can character the group benefit and maintain the stability of society, it seems there is no reason to continue stick to sincerity. But we have to admit that many scientific progress has made so far. It is because that we stick to sincerity, and in the long term it generates benefits to great math. So that the social utility or sincerity depends on the non-utilitarian attitudes of people towards truth. If this attitude is lost, then we will lose the utility of sincerity. Sincerity is important because in the long term and cooperation, we found that if we don’t have a stable commitment to sincerity, we can’t maintain a stable society.So that we start to regard sincerity as an epistemic virtue.