2. Differentiate between cause and consequence, necessary condition and sufficient condition

2.1 Logic reminders

A ⇨ B means :

• B must exist for A to exist ;

• if A exists, then B exists ;

• if B does not exist, then A cannot exist;

• B is a necessary condition for/of A ;

• it is sufficient for A to exist for B to exist ;

• A is a sufficient condition for/B.

Example: A = "make an omelette" and B = "break eggs". It's "enough" to make an omelette to break eggs, just as it's "enough" to make pancakes to break eggs. But: it's...