A critical realist believes that there is a reality independent of our thinking about it that science can study. (This is in contrast with a subjectivist who would hold that there is no external reality — we’re each making this all up!). Positivists were also realists. The difference is that the post – positivist critical realist recognizes that all observation is fallible and has error and that all theory is revisable. In other words, the critical realist is critical of our ability to know reality with certainty. Where the positivist believed that the goal of science was to uncover the truth, the post – positivist critical realist believes that the goal of science is to hold steadfastly to the goal of getting it right about reality, even though we can never achieve that goal ! Because all measurement is fallible, the post – positivist emphasizes the importance of multiple measures and observations, each of which may possess different types of error, and the need to use triangulation across these multiple errorful sources to try to get a better bead on what ‘s happening in reality. The post – positivist also believes that all observations are theory – laden and that scientists (and everyone else, for that matter) are inherently biased by their cultural experiences, world views, and so on.