{ 2. Iota is an intangible particle distinguished from void. }
iota := void or not void.

{ 3. Boolean is a iota of truthfulness. }
boolean := iota.

{ 4. True and false are boolean possibilities. }
true, false := boolean.

{ 5. Truthfulness gives rise to propositional logic. }
not p :=
     p := boolean.

     -> p ?
          true  -> false.
          false -> true.

p and q :=
     p, q := boolean.

     -> p ?
          true  -> q.
          false -> false.

p or q :=
     p, q := boolean.

     -> p ?
          true  -> true.
          false -> q.

p xor q :=
     p, q := boolean.

     -> (p or q) and not (p and q).