Guess is a slang attributed to "theory" that is created by someone about something based solely on their opinions and intentions, without any kind of concrete argument or justification.
Guessing is practiced by people who are unaware of the nature of a given subject, but who insist on trying to explain something taking into account only what they think about the topic.
This word originated precisely from the verb "to find" with the addition of the suffix "ism", giving the idea of being the act of justifying or theorizing something based on a subjective thought or concept ("I think what...").
Example: "Your public policy discourse is full of guesswork."
Among some of the main synonyms for guessing, highlighting: achievism, supposition, presupposition and presumption.
Learn more about the meaning of Assumption.
As a rule, speeches based on guesses are made by ignorant people, who refuse to get a correct information on a particular subject and instead spread rumors or false content among the too much.