An old saying states if something walks like a duck, swims like a duck, and quacks like a duck, it’s probably a duck. That adage is known as the duck test. The duck test is a well-known example of abductive reasoning that is often referenced in everyday conversations. The test suggests that a person can identify an unknown subject by observing that subject's habitual characteristics. It is sometimes used to counter complex arguments that something might not be what it seems.