 The weaker of the large cardinal principles are supported by intrinsic evidence (see  section 3.1).  They follow from what are called reflection principles. These are principles that state that the set theoretic universe as a whole is so rich that it is very similar to some set-sized initial segment of it. The stronger of the large cardinal principles hitherto only enjoy extrinsic support. Many researchers are skeptical about the possibility that reflection principles, for instance, can be found that support them (Koellner 2009); others, however, disagree (Welch &amp; Horsten 2016).