In law, a presumption is an "inference of a particular fact".[1] There are two types of presumptions: rebuttable presumptions and irrebuttable (or conclusive) presumptions.[2]: 25 A rebuttable presumption will either shift the burden of production (requiring the disadvantaged party to produce some evidence to the contrary) or the burden of proof (requiring the disadvantaged party to show the presumption is wrong);[1] in short, a fact finder can reject a rebuttable presumption based on other evidence.[3]: 87 Conversely, a conclusive/irrebuttable presumption cannot be challenged by contradictory facts or evidence.[3]: 87–88 Sometimes, a presumption must be triggered by a predicate fact—that is, the fact must be found before the presumption applies.[4]: 1321–22