However, to justify this, we need an additional general premise, a hypothesis, such a finding to a general causal conclusion. We must assume that there is a condition that is necessary and sufficient with regard to the field (or that is necessary or sufficient) for the phenomenon, and also that this condition can be found in a number of conditions that are limited in one way or another. Indeed, these methods fall within the general class of eliminating reasoning, i.e. arguments for which a possibility is confirmed or justified by the elimination of some or all of its competitors. The assumption is said that there is a reason to find and limit the range of candidates for the role of the cause; The role of compliance will be to exclude enough candidates who were originally admitted to allow for a positive conclusion. We obtain a variant of the method of agreement (1.12) by combining with this hypothesis the following observation: A sentence of one or more positive instances, so that a possible cause, for example. B A, exists in all cases, but for any other possible cause there is a proceeding for which this case is absent. The result is the conclusion that A is necessary and sufficient for P in the P. Mill rule of agreement and states that if, in all cases where an effect is present, there is a single common prior factor C in all of these cases, then C is the cause of the effect. According to the table in this example, the only thing you ate was oysters. Therefore, if we apply the rule of concordance, we conclude that the consumption of oysters is the cause of the disease.
We therefore find that, although we had to identify very different variants of these methods according to the different types of hypotheses used, and that the argument that validates the simplest variants fails when it is permissible for different negations and combinations of factors to be the real cause, there are nevertheless valid demonstrative methods that use even the least strict form of acceptance. , that is, which assume only that there is a necessary and sufficient condition for P in F, which consists, to some extent, of a limited set of possible causes. However, in such a scenario, we must either simply draw (until 8.2) a very incomplete conclusion from the classical observation of differences, or (par 8.12, 8.14, the combination of these two or 8.4) to draw more complete conclusions only from a large number of cases where possible causes are systematically or non-existent. Consider as an example of the two similar countries difference method. Country A has a centre-right government, a uniform system and was a former colony. Country B has a centre-right government, a single system, but has never been a colony. The difference between countries is that Country A easily supports anti-colonial initiatives, while country B does not. The difference method would or would not identify the independent variable as the status of each country as a former colony, the dependent variable supporting anticolonial initiatives. This is because the two similar countries have compared, the difference between the two is whether they were previously a colony or not. This then explains the difference with the values of the dependent variables, the former colony supporting decolonization rather than the country without a history of being a colony. Symbolically, the common method of concordance and difference can be presented as: This argument model illustrates the Mile residue method: many elements of a complex effect are shown to result from reliable causal beliefs of several elements of a complex cause; All that remains of the effect must have been produced by the remnants of the cause.