"Our knowledge is only a collection of scraps and fragments that we put together into a pleasing design, and often the discovery of one new fragment would cause us to alter utterly the whole design (Morris Bishop)." To what extent is this true in history and other such areas of knowledge?
This is true to a very large degree in history and in other areas where it is not possible to do experiments to learn facts objectively.
History cannot help but be a collection of fragments. It is impossible to write the whole history of any one person, let alone of a whole society. So much of a person’s life would be uninteresting, regardless of how important the person was. Much of what happens in society is deemed to be irrelevant for historical purposes. Therefore, history has to be a collection of fragments. So do other areas of knowledge like the study of ancient human origins (limited by the fossil record) or political science (like history, it cannot possibly describe everything that happens in all areas of politics.
These fragments need to be put together in a “pleasing design.” In other words, people take the evidence and decide what narratives they want to tell. They say that the 1950s in America were a time of conformity even though we know many people did not conform. They say that the Great Depression was a time of terrible hardship even though there were many Americans for whom things were not that bad. Studies of human origins have based their views of what early humans were like on their own personal views of what human nature is. These people are all arranging the scraps in a design that pleases them.
Thus, this statement is true to a great degree for history and other such disciplines. Such disciplines must pick and choose what will be seen as relevant and what will be discarded. They put the fragments together into narratives that make sense to them at the time. This can all change if the right sort of new scrap of information is discovered.