presumptions

Presumptions are assumptions or inferences taken to be true for purposes of reasoning, decision making, or legal procedure, often used as starting points when evidence is incomplete. They help guide argument and judgment but are typically open to challenge by contrary evidence or argument.

In law, presumptions are rules that allow a fact to be inferred from another fact. They can be rebuttable (the presumption can be overcome) or irrebuttable/conclusive (binding and not dispelled by evidence). Presumptions can also shift the burden of proof, influencing how cases are argued and decided. Common examples include the presumption of innocence in criminal trials, the presumption of legitimacy for children born within wedlock, and presumptions about the regularity of official acts. Some presumptions, such as death by absence after a specified period, may become conclusive.

In logic and evidence, presumptions function as provisional assumptions accepted for the sake of argument or inquiry. They are justified by coherence with existing principles, past experience, or policy considerations, and they remain subject to revision in light of new information or stronger contrary evidence.

In statistics and probability, presumptions are related to prior beliefs or prior probabilities pressed into formal reasoning, especially in Bayesian frameworks. A prior expresses what is assumed about a parameter before observing data, and it is updated as evidence accumulates.

Presumptions can streamline decision making but risk bias if applied rigidly. They are most effective when transparent, contestable, and subject to revision in light of robust evidence.