 By stressing the distinction between collapse and decoherence, Osvaldo Pessoa (1997) criticized the assumption that decoherence solves the measurement problem. Following Pessoa’s view, Castagnino, Sebastian Fortin, and Lombardi (2010) deepened the criticisms of the orthodox approach to decoherence (see also Lombardi, Fortin, and Castagnino 2012; Fortin and Lombardi 2014, 2017), proposed a new approach for closed systems (Castagnino and Lombardi 2004; Fortin and Lombardi 2018), and developed a general conceptual framework for decoherence in closed and open systems (Castagnino, Laura, and Lombardi 2007). On the basis of this new perspective, the research group offered a particular view of the classical limit of quantum mechanics (Castagnino and Lombardi 2005; Fortin and Lombardi 2016) and applied it to the problem of defining the quantum ergodic hierarchy (Castagnino and Lombardi 2007; Gómez and Castagnino 2014).