No proposition should be accepted as definitely true until one has 100% perfectly justified complete certainty of the truth of this proposition.

100% perfectly justified complete certainty (PJCC) can only be achieved when the truth of a proposition can be totally verified entirely on the basis of the meaning of its words.

A proposition must be considered to be possibly true until it is known to be necessarily false.

(Modal Logic):

Possibly(P) <–> Not(Necessarily) Not(P)

Necessarily(P) <–> Not(Possibly) Not(P)

A proposition cannot be considered to be necessarily false until this proposition results in an inescapable direct contradiction.

Even an infinite amount of (inductive logic) evidence does not amount to an infinitesimal amount of (deductive logic) proof.

Unless reasoning begins with premises that are known to be true with 100% perfectly justified complete certainty (PJCC), reasoning is not sound even if it is otherwise valid.

Reasoning can only be 100% perfectly trusted when it is categorically exhaustively complete, thus has no gaps.

When reasoning begins with a categorically exhaustively complete set of mutually exclusive premises and this reasoning is valid, one derives 100% perfectly justified complete certainty (PJCC) that exactly one of these conclusions is based on sound reasoning.

All logical error boils down to the non sequitur fallacy. All correct reasoning involves the set intersection of the semantic meanings contained within its premises.