This paper is an investigation of the relation between personal and social conditions of knowledge. A coherence theory of knowledge and justification is assumed, according to which incoming information is evaluated in terms of background information. The evaluation of incoming information in terms of background information is a higher order or metamental activity. Personal knowledge and justification is based on the coherent integration of individual information. Social knowledge and justification is based on the coherent aggregation of social information, that is, (...) the information of individuals belonging to the social group. Personal justification and consensual justification are based upon personal and consensual probabilities respectively. Consensual and personal probabilities may differ, but under salient conditions personal probabilities will coincide with consensual probabilities and consensual probabilities will coincide with truth. (shrink)