The standard against which modern theories of scientific explanation are measured is Hempel's Deductive–Nomological (DN) model[Hempel] in which nomological refers to scientific laws, and deductive implies a series of justifiable steps. That is, explanations are expressed as a series of deductive steps ultimately relying on one or more laws of nature.
The Inductive–Statistical model (IS)[Hempel] is similar except that it makes its generalizations inductively based on statistical laws.