The void-based structure of Peirce's and Spencer Brown’s iconic logics challenge a foundational assumption of Western thought, that Rationality requires Dualism.
Duality is subtly embedded within the arithmetic and algebra of numbers as inverse operations, as the self-similar structure of repeated addition and multiplication, as polarity of value, and as the object/process distinction. Duality is embedded in string notation as group theoretic structure (commutativity, associativity, arity), as absence of parallelism in both expressions and processes, as the semantics/syntax barrier, as forced representation of both relevant and irrelevant expressions, and as the Exclusion of the active Agent (the mathematician) from the Notation.
Dualism dominates logic as the concepts TRUE and FALSE and as the dual perspectives of AND and OR. In contrast, the logic boundary ⟨ ⟩ can be interpreted as TRUE, in which case FALSE is the void within TRUE. Since FALSE is void-equivalent in iconic logic its non-existence makes Laws of Form a logic of Unity rather than duality. Truth is confounded with existence. A distinction, as represented by a single boundary, accommodates both independence and unity.
Context, concept and content are a singular system.
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Bricken, Iconic Arithmetic Volume III: The Structure of Imaginary And Infinite Forms, pdf 
, p. 383–384.