"Conditio sine qua non" is a Latin phrase that translates to "condition without which not." It refers to a necessary condition or prerequisite that must be present for a particular outcome or event to occur. In various contexts, including law, philosophy, and logic, it is used to denote an essential factor that is indispensable for a certain result to happen.
For example, in legal contexts, if a party seeks to prove causation, they may argue that a specific action was a conditio sine qua non for the harm that occurred, meaning that without that action, the harm would not have happened. In a more general sense, it's applied to any situation where certain conditions must be met for an effect to take place.