Final answer:
A presupposition is an idea based on belief without proof, whereas a scientific theory is an evidence-based explanation. The theory of evolution, for example, is supported by substantial scientific evidence, distinguishing it from a mere presupposition.
Step-by-step explanation:
An idea that is based on belief and not on proof is best described as a presupposition. This term refers to something that is taken as true without evidence to support it. In contrast, a scientific theory is an explanation that is supported by substantial evidence and consistent results from experiments. Although the common use of the word "theory" might imply a guess or a hypothesis, in scientific terms, it represents a comprehensive explanation that is based on evidence.
For example, the theory of evolution is supported by evidence from various scientific fields, making it much more than a mere belief or presupposition. Therefore, when discussing scientific terminologies, it's important to recognize that a theory is not a random guess but rather a well-substantiated explanation.