Environmental Kuznets Curve ( EKC) theory has evolved over several decades from its initial intuitive conception to the complex theoretical models of today. Through successive steps of empirical and theoretical debate, a quadratic relationship between income and environmental degradation has been proposed, criticized, defended, and criticized again.

  Along the way, each finding have new look at the subject. Critic that is provided by Mazzanti et al. (2007) and Stern (1998) is that instead of attempting to gain insight into the underlying mechanics of an EKC theoretical foundation, there are undue focus on exploring empirical regularities among a large set of variables. These critics from opponent and supporter cause researcher to review their approach and take more concerns on details and methodology of EKC theory that make the way of theoretical works.