Critical rationalism rejects the classical position that knowledge is justified true belief; it instead holds the exact opposite: that, in general, knowledge is unjustified untrue unbelief. It is unjustified because of the non-existence of good reasons. It is untrue, because it usually contains errors that sometimes remain unnoticed for hundreds of years. And it is not belief either, because scientific knowledge, or the knowledge needed to, for example, build an airplane, is contained in no single person's mind. It is only what is recorded in artifacts such as books.