Transmission: Principles of transmission of justification, knowledge, and other epistemic notions have been subject to extensive investigation and discussion in the recent epistemological literature. Some discussions zoom in on principles of transmission within a single agent. For instance, there is an extensive literature on transmission failure in relation to antisceptical arguments: does Moore’s controversial proof of an external world fail to transmit warrant from the premises to the conclusion, because one of the premises cannot be warranted antecedently and independently of the conclusion? Epistemologists also wonder whether inferences from non-knowledge can ever lead to knowledge. Other discussions concern the transmission of true belief, warrant or knowledge between agents—the discussion of testimonial warrant and knowledge being a prime example, another being the debate over whether certain arrangements (such as free speech) do better in terms of promotion of true beliefs in groups of agents than alternative arrangements.