Everything must either be or not be.

As per Lesson XIV in William Stanley Jevons' book Elementary Lessons in Logic Deductive & Inductive (1870)...

"These laws describe the very simplest truths, in which all people must agree, and which at the same time apply to all notions which we can conceive. It is impossible to think correctly and avoid evident self-contradiction unless we observe what are called the Three Primary Laws of Thought, which may be stated as follows:

1. The Law of Identity. Whatever is, is.
2. The Law of Contradiction. Nothing can both be and not be.
3. The Law of Excluded Middle. Everything must either be or not be.

Though these laws when thus stated may seem absurdly obvious...I have found that students are seldom able to see at first their full meaning and importance."

It is interesting to note within 21st century American political, social even religious contexts upon selecting any issue thus impetuous rants posing as commentaries, any topic thus slanderous brawls posing as debates, to find all three laws grossly ignored by the constant contending of two or more disharmonious thoughts as though observably, determinably, logically, ethically harmonious. My fellow countrymen are fools in the making if not well made.

Come let us Reason. Peace is always a Choice.
Study, Ponder, Labor, till last Breath.