The term ‘logical’ does not here refer to the junctors defined in propositional calculus, but instead to the fact that these relations lack concrete semantic content. Unlike concrete interpropositional relators, the conjunctions coding logical relations do not subordinate one of the propositions joined by them. Instead, the semantic relationship is more symmetric, the two propositions are on the same level. This is even true of conditional constructions: the protasis of a conditional differs from propositions bearing a semantically more specific relation by its relative independence. Needless to repeat, things may be different at the level of language-specific structure.
In addition to their syntagmatic relation, the objects related by a logical relation bear a paradigmatic relation, viz. one of similarity, to each other (Blühdorn 2017, §3.1). This regards, first of all, their level in the hierarchy of propopositional objects: Semantically, any kind of entity from utterance down to situation may be linked by a logical relation. Some such relations are even applicable below the level of the situation. On the expression side, this means that corresponding connectives may connect anything from sentences down to words. The only condition is that the components thus related must be of the same propositional level. For specific constructions, there may be additional constraints on semantic or structural parallelism between these relata. Languages and their relators differ in the constraints that the impose on the category of their relata (Haspelmath 2006). On the other hand, constructions produced by a logical relation are rarely totally symmetric in the sense that their components can freely swap positions.
Logical interpropositional relations are essentially concerned with the structuring of discourse in terms of the reality or non-reality of the connected propositions. We will be speaking of asserting vs. not asserting a proposition, where ‘assertion’ does not mean declarative illocutionary force, but instead is the opposite of ‘presupposition’ and ‘hypothesis’.
This distinction yields the principal subdivision of this section:
- assertion: coordinative junction
- presupposition: condition.
Each of these relations cross-classifies with other cognitive parameters, chiefly
- polarity of the clauses,
- clause type and modality of the clauses.
In each logical relation, the classification arrives at structural types involving
- a certain number of linked clauses,
- a certain order of the clauses,
- syndetic vs. asyndetic structure, i.e. use of certain connectives,
- number of connectives per number of coordinated elements,
- some degree of structural parallelism of connected elements,
- omission of elements under identity across propositions (ellipsis).
Several of these parameters cross-classify with each other. For instance, ellipsis is especially common if the propositions involved have some degree of parallelism and differ only in the polarity of an element in some syntagmatic position. Refer to corresponding sections of the semasiological description.