Since the assumptions are still relaxed, the agreement method requires stronger and stronger observations. For example, in 6.12, which is a variant of the positive method with the assumption that the necessary and sufficient condition may be a disjunction of possible causes or negations, the required observation is such a number of positive instances, so that a possible cause, for example. B A, is present in each, but that there is a case for any possible combination of other possible causes and their negations in which this combination exists (i.e., if there are other possible causes, we need 2n different instances). This observation will air condition any district that does not contain A and will show that the necessary and sufficient condition (A or…) is and therefore A itself is a sufficient condition for P in F. A corresponding variant of the negative tuning method (5.14) shows that (A…) is a necessary and sufficient condition, and therefore that A itself is necessary – a strange reversal of the rollers, because in the simplest variants, the method of positive tuning was used to recognize a necessary condition and the negative condition a sufficient condition. Unlike the four previous inductive methods, the method of accompanying variation does not involve the elimination of any circumstances. The change in size of one factor causes another factor to change in size. Understanding causality requires an understanding of the concepts of sufficient and necessary conditions. A sufficient condition occurs whenever an event guarantees that a different event occurs. A necessary condition means that one thing is essential, obligatory or necessary for something else to be achieved. By highlighting the necessary hypotheses and presenting disposal methods as deductible arguments, we have abandoned any excuse for methods like this to solve or eliminate the “problem of induction.” To the extent that the necessary observations are possible, the definitive justification for any application of any of these amplative induction methods depends on the justification of the hypothesis used; Since this rate is general, it will probably have to be supported by another type of inductive, or at least non-deductible, argument. But we must leave aside this question of definitive justification. 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.