Indirect knowledge is a kind of Knowledge.
It is characterised by relations among contents in the memory that are formed as a result of a Logic | logical operations.
Examples :
And so on. Although the actual events/objects were not witnessed, there is still a logical relation here, i.e. knowledge is formed indirectly.
Notice that one must have a Direct Knowledge | direct knowledge of at least one instant of the object/event before one can form a meaningful relation. The logical operations are based on past experiences, and can be an inference, deduction/induction, guess, probability or even an exact number etc.
Indirect knowledge is very useful, but less reliable, as there is a low amount of certainty about it.