We must have a common set of assumptions whenever we study nature and compare observations with other human beings. Assumptions are accepted as true or certain to happen without proof.
Most of the common set of assumptions are so basic that they are often not even declared. We take many complex interactions for granted simply because we are intensely familiar with them. In instances where there is a widely held consensus about the interpretation of an observation, there is little evidence to suggest potential variations in specific phenomena. Einstein’s proposal that time is relative to speed was a surprising revelation. The field of quantum physics brought about an unforeseen level of uncertainty surrounding the nature of variables, particularly the concept of particle-wave duality.
Some other assumptions are more specific and need a further declaration. We use the SI system for measurement comparison; we assume objectivity when there is repeatability. We declare which variables have been assumed to be constant during an experiment. We need to declare the conditions for the repeatability of the experiment and the like. Different observers must be able to arrive at the same outcome for the experiment.
