phil 2303

phil2303intro to logic

the ‘4th’ law of logic

law of sufficient reason

Gottfried W. Leibniz

For every entity x, if x exists, then there is a sufficient explanation why x exists.

For every event e, if e occurs, then there is a sufficient explanation why e occurs.

For every proposition p, if p is true, then there is a

sufficient explanation why p is true.

• In other words, the principle of sufficient reason states that anything that happens does so for a reason: no state of affairs can obtain, and no statement can be true unless there is sufficient reason why it should not be otherwise

This led to two schools of thought regarding this 4th law

(which is why it is not included in most pedagogical lessons of logic)

determinismIn a deterministic system, every action, or cause, produces a reaction, or effect,

and every reaction, in turn, becomes the cause of subsequent reactions.

non-deterministicIn a non-deterministic system, the putative ability of various agents allow

them to make choices free of certain kinds of restraints (i.e. free will).

logic exercises