First Principles or Axioms would be the terms you're looking for
Started (at least in Western science) with Euclid's Elements:
It is possible to draw a straight line from any point to any other point.
It is possible to extend a line segment continuously in both directions.
It is possible to describe a circle with any center and any radius.
It is true that all right angles are equal to one another.
("Parallel postulate") It is true that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, intersect on that side on which are the angles less than the two right angles.
All of these are taken as the base assumptions for the rest of the logical proofs for euclidian geometry.
With physics, I'd say the thermodynamic laws are the axioms.
With political science, the axioms aren't as clearly defined. Marx and Engels are really the first to try and lock them down with the concepts of class struggle and Labor == Value ("all history is the history of class struggle" is one of Marx's big axioms). Marx also uses thermodynamic principles in the context of political economy with Labor standing in for energy.