Mills` rule of understanding states that if, in all cases where an effect occurs, there is a single prior C factor common to 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. One of the main characteristics of scientific methodology is verification and falsification. Remember J. 4 that an appeal is made to Dieun if we conclude for lack of evidence that something is the case or not. While there are times when a lack of evidence should lead to a judgment that the original claim is not substantiated (as in a criminal court), this is not the case in scientific practices. The method of accompanying variation says that if, in a number of situations that lead to a particular effect, we find some ownership of the effect that varies with variation in a factor common to these situations, then we can infer that factor as a cause. This reasoning illustrates Mill`s method of residues: many elements of a complex effect are demonstrated by reliable causal beliefs from several elements of a complex cause; All that remains of the effect must have been produced by the remnants of the cause.
Note that if we accept the truth of all the relationships of cause, this method becomes an application of the deductive argument. John Stuart Mill (1806-1873) was an English philosopher who wrote on a wide range of subjects ranging from language and science to political philosophy. The so-called „mill“ methods are five rules for the search for the causes he has proposed. It has been assumed that some of these rules were in fact discussed by the famous Islamic scientist and philosopher Avicenna (980-1037). This method is also generally known as the most similar system design in the context of comparative policy. Even simply referred to as the „common method,“ this principle represents only the application of methods of concordance and difference. Mills methods should not come as a surprise, as these rules articulate some of the principles we use implicitly in causal reasoning in everyday life. But it is important to respect the limits of these rules.
Mills` methods are five methods of induction described by the philosopher John Stuart Mill in 1843 in his book A System of Logic.  They must shed light on issues of causation. In this case, you are the only one who is not sick. The only difference between you and the others is that you didn`t make a salad. It`s probably the cause of other people`s illnesses. It is an application of the method of difference. This rule says that if you have a situation that leads to an effect, and another that does not, and the only difference is the presence of only one factor in the first situation, we can infer that factor as the cause of the effect. This is an example of mills method of simultaneous variation: The evidence seems to show that there is a direct correlation between the degree to which the cause occurred and the degree to which the effect occurred.
This is consistent with our usual principle that effects are generally proportional to their causes. This is indeed a sophisticated version of the Common Method, in which we notice not only the occurrence or non-presence of the terms of cause, but also the extent to which each of them took place. If the purpose of using Mills` methods was to prove that one event is the cause of another, we would do worse. Our inability to take into account all kinds of circumstances (even those that we do not think are relevant) will often lead us to confuse the true cause of an event. In addition, the methods promote the identification of individual causes and overlook the fact that many interesting effects can result from a complex combination of partial causes.