Strong scientific theories set up gambles. A theory should lead to hypotheses that, when tested, could fail to support the theory—in other words, falsifiability is a characteristic of good theories (Popper, 1963).
I find it interesting that Harlow was willing to take a big gamble with the research that he decided to do. This is interesting to me because, personally, when I decide to take on research, it’s because I usually have an idea of what the conclusion will be. However, I do know that it isn’t unusual for things to go the opposite of the way they were planned. Why do we tend to take the safer route when doing things?