The absolute truth is like an asymptote, you can get closer and closer to it but never really reach it. In the end, it is impossible to prove a theory to be absolutely, without a doubt, correct. .
The same holds true for proving a theory to be false. It would seem that if a theory does not pass an experimental test then it would lead to straight out rejection, but at the same time it is always possible to find some kind of support for the theory. In reality, failing an experimental test only leads to questioning of the data or modification of the theory. As Goldstein points out, "no theory fits perfectly every conceivable experiment."" In the case of John Snow and cholera, his theory was faced with a case that outright proved his ideas to be wrong. A man drank a glass of a cholera victim's evacuations, the exact thing that was thought to cause the disease, by mistake and yet did not get sick. Yet this outright contradiction did not cause the theory to lose its basic importance, and it still helped to prevent many future outbreaks of cholera. Falsification by experiments can therefore only tell us that there is a problem, but not whether the problem exists in the theory, the experiment, or one of the many other variables involved. .
If there is no way to prove the absolute validity or falsity of a theory, how has science been able to progress? In the past many philosophers have attempted define progress as something other then simply moving closer to the truth. Two theories that perhaps provide us with the greatest understanding of progress in terms of science and culture are T.H. Kuhn's model of paradigms and revolutions, and Larry Laudan's model of research traditions. If science is viewed in a nave sense, where every theory is just a logical continuation of the previous one and the nature of change is frequent and gradual, then progress is easy to see because each new theory is simply better then its forerunner.
