Based on hypothesis and theory rather than experiment or empirical evidence.
Presumed without analysis.
Self-evident, intuitively obvious.
Developed entirely from scratch, without deriving it from existing languages.
In a way based on theoretical deduction rather than empirical observation.
Based on reasoning, evidence and good judgement.
Properly substantiated.
Of a binary relation: such that every non-empty subset of the relation's domain has a minimal element with respect to the relation.