The difference in method used is the canon of elimination - "When no antecedents can be left without the consequent disappearance, such antiquity must be the cause or part of the cause."

In this method two examples are collected. In these two examples one is positive example, while the other is negative. The material required to apply the differential method is a jar filled with air, a vacuum jar, and a bell. Sound will be heard in the presence of air. This is called a positive example. In the negative example, air is absent from the jar and the sound will not be heard.

The following are the disadvantages are as follows :

(1) The method of difference does not enable us to deal completely with the plurality of causes the method of difference can only prove that a particular antecedent is the cause in a given case. But cannot prove that it is the only cause.

(2) The method of difference does not enable us distinguish a cause from a condition. The introduction of a new element is not necessarily the sole cause of any change which may happen.

(3) The method of difference cannot be applied to reason directly from logic. In the experiment, we can move from cause to effect, but not back from effect. The effects are not under our control. Since the method of the method is essentially a method of experimentation, the method also cannot be applied to logic with direct effect.