A more thorough explanation:

Definition: An a priori assumption is an assumption that is presumed to be true without any assessment of the facts or without further proof. A priori is a Latin term that refers to a theoretical deduction made on a subject without a precise and detailed observation of the objective elements at hand. On the contrary, a posteriori refers to the reasoning that stems from the observation of known facts or past events, rather than the making of an a priori assumption or prediction, i.e. before conducting such observation.

Example: A common example of an a priori assumption is the belief that all swans are white. This assumption was made by Europeans before they had ever seen a black swan, which was later discovered in Australia. Another example is the assumption that all dogs are friendly, which may not be true in all cases.

These examples illustrate how an a priori assumption can be incorrect or incomplete without further observation or evidence. It is important to question and test assumptions to ensure they are accurate and reliable.