The five inductive principles proposed by J. S. Mill as those regulating scientific enquiry. They are

1. (i) The method of agreement. If two cases of a phenomenon share only one feature, that feature is their cause or their effect.

2. (ii) The method of difference. If a case in which a phenomenon occurs and one in which it does not differ by only one other feature, that feature is the cause, or a necessary part of the cause of the phenomenon, or it is its effect.

3. (iii) The joint method of agreement and difference. This combines the previous two.

4. (iv) The method of residues. If we subtract from a phenomenon what is already known to be the effect of some antecedent events, then the remainder is the result of the remaining antecedents.

5. (v) The method of concomitant variation.

Phenomena that vary together are linked through some causal relationship. While the methods make good scientific sense they do depend upon a preceding analysis of the relevant factors, and they are not immediately applicable to cases where causation proceeds more ‘holistically’, or in virtue of a field of interlocking factors.