 Different systems of informal logic vary in a number of ways — often, by incorporating formal, rhetorical, dialectical and other methods of analysis to a greater or lesser extent. Many systems propose unique approaches or mix methods that they borrow from other systems. Groarke 2020 has outlined a “BLAST” approach to the identification and definition of systems of informal logic. It defines a specific informal logic system I, as I = {B,L,A,S,T}, where: