presumption

Presumption is a belief or conclusion that something is true based on probability, evidence, or authority, without requiring direct or complete proof. In everyday language, people act on presumptions to guide decisions. In formal contexts such as law and logic, a presumption is a rule or principle that a fact exists or a consequence follows unless opposing evidence is introduced.

In law, presumptions allocate the burden of proof or rationalize outcomes. They can be conclusive (irrebuttable), meaning the fact is accepted as true regardless of contrary evidence, or rebuttable, allowing evidence to overcome the presumption. Two broad categories are presumption of law and presumption of fact. Presumption of law imposes a legal conclusion; presumption of fact arises from common experience or probabilistic reasoning about a situation.

Presumptions play a central role in criminal and civil proceedings. Presumption of innocence requires the state to prove guilt rather than the defendant proving innocence. Other examples include the presumption of legitimacy for children born to married parents, and the presumption of regularity in official acts. In civil cases, presumptions can affect who bears the burden of proof or what conclusions are considered likely.

Critics warn that presumptions can perpetuate injustice if left unchecked, particularly when irrebuttable or outdated. Rebuttable presumptions provide a mechanism to adjust beliefs in light of new evidence, while many legal systems require explicit standards of proof, such as beyond a reasonable doubt or preponderance of the evidence. Presumption thus functions as a tool to streamline reasoning while remaining subject to challenge.