What is the action of making an assertion based on incomplete evidence called?

Making an assertion based on incomplete evidence is termed conjecture. This term specifically refers to the formation of opinions or conclusions based on insufficient information or lack of definitive proof. When someone makes a conjecture, they are often filling in gaps with what they believe to be true, despite the absence of comprehensive evidence to support their claim. This process often involves a degree of speculation and can lead to potential hypotheses that require further investigation to confirm.

In contrast, inference involves drawing a conclusion from what is already known or presented, typically relying on logical reasoning rather than incomplete data. Guessing generally implies a lack of any logical reasoning or prior knowledge, making it less related to the methodical nature of conjecture. A theory, on the other hand, is a well-substantiated explanation of an aspect of the natural world that is based on a body of evidence and has withstood repeated testing and scrutiny. Thus, conjecture is the most accurate term for making assertions from incomplete information.