 If facts can be negated, then the negation of fact \(x\) (if any) will have existence-set \(W \setsub \ES(x)\). If facts can be conjoined, then the conjunction of the facts in set \(G\) (if any) will have existence-set \(\CES(G)\). And if facts can be disjoined, then the disjunction of the facts in set \(G\) (if any) will have existence-set \(\DES(G)\). One can then understand why we call these principles ‘Boolean’.