According to some theories of knowledge, it is impossible for someone to know something if the person’s belief is based upon a false belief. But an appeal to social aspects of belief formation casts this criterion into doubt. For it is not uncommon for a helpful individual to convey a point to someone else using a falsehood. Consider the following case, which appears in a recent publication of mine:
Natasha is a spy in the field. Messages to her from Headquarters often are detected by enemy intelligence, and Headquarters is aware of that. Today, Headquarters needs to communicate to Natasha that her contact will be at the train station at 4:00 pm, but Headquarters cannot directly tell her that. However, Headquarters knows that Natasha happens to have a false belief that the train from Milan is arriving at 4:00 pm. It really arrives at 8:00 pm; also, assume that there are no signs posted at the station indicating what time it will arrive. So Headquarters sends a communiqué to Natasha stating that her contact is on the train from Milan. She then forms the justified belief that the contact will be at the station at 4:00 pm (call this proposition C). C is true.
This case involves a peculiar form of testimonial evidence. Typically, one acquires knowledge via testimony when a cooperative testifier states truths. But this case maintains the spirit of knowledge via testimony – the testifier, Headquarters, is being epistemically cooperative in conveying a true target proposition to a Natasha, albeit in a somewhat unusual manner.
I submit that it is a case where Natasha knows that C, even though her belief is based essentially on two false beliefs. However, I should add that this particular case has some complications (which I discuss in the paper) and not all who hear the case take it to be a case of knowledge. At the very least, it is a case where Natasha is, to use a phrase introduced by Robert Nozick, tracking the truth of C. In other words, had the contact not been planning to arrive at that time, Natasha would not have formed the belief that the contact is at the station at that time since Headquarters would not have sent that communiqué to her.
On the account of knowledge I am developing, knowledge is justified belief which is formed in an environment which is conducive to believers forming true beliefs which are relevantly similar to the belief in question. This can happen when another person is somehow overseeing the epistemic environment for the purpose of conveying other truths to the believer, even if the overseer uses falsehoods to transmit the information. In the spy case – or so I claim – both Natasha’s belief was justified, and it was formed in an environment conducive to her forming a true belief about C. The fact that she believed that C via a falsehood does not undermine her knowledge of it.