Presupposition (noun)

1. An assumption made in advance in order to make a certain inference or determination.
2. A requirement or condition that must be met in advance.

Origin:

Late 16th century, from latin prae- "before" + suppositus "put in place".

Examples:

1. The presupposition of his argument was that all people are equal.
2. The presupposition for their relationship was trust.
3. Her presupposition was that everyone would show up on time.
4. The presupposition of the experiment was that temperature affects reaction time.
5. The presupposition for this theory is that the universe has a beginning.