knowledge de re knowledge, with respect to some object, that it has a particular property, or knowledge, of a group of objects, that they stand in some relation. Knowledge de re is typically contrasted with knowledge de dicto, which is knowledge of facts or propositions. If persons A and B know that a winner has been declared in an election, but only B knows which candidate has won, then both have de dicto knowledge that someone has won, but only B has de re knowledge about some candidate that she is the winner. Person B can knowingly attribute the property of being the winner to one of the candidates. It is generally held that to have de re knowledge about an object one must at least be in some sense familiar with or causally connected to the object.
A related concept is knowledge de se. This is self-knowledge, of the sort expressed by ‘I am —— ‘. Knowledge de se is not simply de re knowledge about oneself. A person might see a group of people in a mirror and notice that one of the people has a red spot on his nose. He then has de dicto knowledge that someone in the group has a red spot on his nose. On most accounts, he also has de re knowledge with respect to that individual that he has a spot. But if he has failed to recognize that he himself is the one with the spot, then he lacks de se knowledge. He doesn’t know (or believe) what he would express by saying ‘I have a red spot.’ So, according to this view, knowledge de se is not merely knowledge de re about oneself.
See also DE DICTO. R.Fe.