 In what follows, we will represent the conditional operator by the symbol \(&gt;\). We distinguish three main layers of syntactic complexity. Let \(L_0\) be a propositional language capable of building factual sentences from atoms with the help of the usual Boolean connectives (\(\neg\), \(\wedge\), \(\vee\), \(\supset\) and \(\equiv\) for negation, conjunction, disjunction, material conditional and material equivalence, respectively). Then \(L_1\) is the extension of \(L_0\) with flat conditionals, such that if \(A\) and \(B\) are in \(L_0\) then \(A&gt;B\) is in \(L_1\). And \(L_2\) is the extension of \(L_0\) and \(L_1\) allowing free combinations of all connectives, including arbitrary nestings of conditionals.