There are at least five possible sources of knowledge.
1 all sources of authority such as tv,radio,newspapers,parents,teachers and friends etc.
2 reason,the power of thought
3 empiricism,our five senses
4 intuition,the power of attaining direct knowledge without rational thought
5 tacit knowledge
Explicit knowledge is knowing "that"-all the facts you know. Tacit knowledge is knowing how.
There is no explicit knowledge on how to console a distressed friend or how to end a romantic relationship or how to resolve a moral disagreement. This involves tacit knowledge.
