Karl Popper's philosophy of science requires us to be overly critical of scientific theories.

1. HistoryDirect argument against the content of a theory is not the only way to demonstrate a logical problem with it. For instance, if it is found that the application of an ethical theory may require us to torture and murder innocent people to increase the hedonistic pleasure that might be derived from others in the community, demonstrating such a feature may act as a valid counter-example that shows an inadequacy of the ethical theory since it contradicts our basic intuitions of morality. In the same way, the historical argument against Popper’s falsificationism presents numerous counter-examples that demonstrate significant scientific progress occurring in ways that Popper condemns as unethical and that do not hold to the limitations called for by his philosophy. It is a type of argumentum ad absurdum in that it examines the conclusions that extend from Popper and demonstrates an absurd conclusion: that theories considered as an improvement over previous theories (i.e. heliocentrism vs. geocentrism) should have been considered falsified and abandoned from its inception due to the dictates of an overly critical philosophy of science. a. Duhem-Quine problemMany of the problems with Popper’s theory originates in the Duhem-Quine problem, which argues that falsification can only be applied to individual hypothesis statements (H), but that theories are constructed by not only hypothesis statements that make observational predictions (O), but that hypothesis statements are inevitably accompanied by auxiliary assumptions (A). Instead of H -> O, ~O:: ~H the Duhem-Quine problem states that any theory also contains assumptions adjoined with the hypothesis: H^A -> O. ~O:: ~(H^A). Because of this we are unable to logically determine whether it is a failure of the hypothesis we are testing or simply the auxiliary assumptions. Popper accepted this as a problem and attempted to overcome it by stating that scientists must make their own decisions in these cases according to their own interpretations of the data as to whether the failure is due to H or A, further undermining his theory since it makes any theory ultimately unfalsifiable depending on the interpretations of the scientist. In order to contain what is allowed in this case, Popper forbids the practice of ad hoc changes in a theory in order to fit the theory to observations. This criteria is also problematic, however, as it still discounts many instances where utilizing this practice has proven highly effective in scientific practice. b. Copernican RevolutionThe Copernican theory of heliocentrism contained many inconsistencies between what was predicted and what was observed. For instance, the theory stated that Venus should appear six times brighter than at other times, however, this observation failed to present. To the scientists of the day it appeared to be a failure on the part of the theory, yet they continued with it anyway. It was also predicted that if the planet was indeed moving then an object dropped from the top of a tower would not fall directly below the spot from which it was dropped, but would land next to it due to the motion of the earth. It was not until Galileo improved upon the theory that such inconsistencies were solved. Most theories begin in a similar way, where the initial predictions made by it are falsified. It is because scientists do not accept falsification as their conclusion, but continue to pursue it that they often find that after clarifying their assumptions that they find they were progressing after all. Observations such as these throughout the history of science led the philosopher Thomas Kuhn to conclude that successful science does not follow a rational process, but works best by following an irrational process based on the decisions of the scientists themselves.Popper was forced to accept that his initial theory was overly narrow and the holism proposed by Duhem and Quine. He modified his falsificationism as mentioned above to accommodate for this problem and grant scientists the ability to decide to risk pursuing a falsified theory, further undermining his goal of providing a logical foundation for science. However, he still attempted to limit this practice by 1) requiring a scientist to state under what terms he would consider his theory falsified from the beginning, 2) forbidding the practice of looking back on a theory after observations are made in order to improve the theory, and 3) requiring a scientist to abandon his theory as falsified once the given criteria had been met. Even this, however, is overly constraining, as demonstrated by Imre Lakatos. Lakatos found further examples of processes that went beyond these bounds set up by Popper, yet eventually became highly successful theories. c. Bohr’s atomic modelThe atomic model of Bohr was known to be inconsistent and falsified for decades, but scientists continued to use it as a working model anyway. They also improved the theory by looking backwards after observations. This is the primary example used by Lakatos to criticize Popper’s account of falsificationism and support his own falsificationist account that would allow for backward-looking adjustments to be made, as well as allow for inconsistencies within the realm of science in order not to discount valuable processes that Popper would throw out and so, severely limit the effective practice of scientists. "'All theories are born refuted,' Lakatos liked to say; they abound in inconsistencies and anomalies-they are always already falsified as it were. In addition, many research programmes-including Newtonian mechanics, Maxwell's electromagnetic theory, or relativity, or evolutionary theory-also could never have identified conditions in advance that, if observed, would justify giving up the entire research programme (http://alturl.com..., 109)."2. ProbabilityThere are instances where probability is falsifiable. However, many of the important uses of it in science are ruled out by Popper’s theory because they do not meet his rigorous standards of falsifiability. For instance, science says there are specific half-lives to various types of radiological material. There is a good possibility that we may observe an amount of this material for the duration of its half-life and find that 50% of it has decayed, but this is only a probable prediction that increases with the number of observations we make. Since this theory is based on probability, however, we may also find that the prediction is not observed. This failure would not falsify the theory because it is based on probability. If we accept Popper’ philosophy we would be forced to discount such theories as unscientific, yet this is generally considered an unacceptable conclusion that implies instead that such a theory consists of overly narrow criteria3. SupportThere was no misrepresentation in my description from R2. From Con’s source in R2: “For Popper, a theory is scientific only if it is refutable by a conceivable event. Every genuine test of a scientific theory, then, is logically an attempt to refute or to falsify it, and one genuine counter-instance falsifies the whole theory (Sec. 4).”Regarding the bridge scenario we are again talking about the outcome of applying Popper’s philosophy to the field of science and finding that we meet with absurd results. Con states that we can take the fact that a theory has repeatedly passed attempts at falsification into account in making our decision. We can do this because it is the intuitively rational thing to do. Popper’s theory takes away this intuition by discarding the notion of support and leaves us with no basis to make the decision to choose the tested (A)or untested theory (B). Any attempt to allow us to take the history of A into account is to try to “have your cake and eat it too.” One can allow for this decision only by disregarding the implications of Popper’s theory in the practical situations that the bridge scenario points out.