Consider the following argument: If we start requiring automatic weapons owners to pass an automatic weapon's safety test, then it's likely that we will start to require gun owners to pass a gun safety test. If we start requiring gun owners to pass a gun safety test, then it's likely that we will start to require knife owners to pass a knife safety test. If we start requiring knife owners to pass a knife safety test, then it's likely that we will start to require toy owners to pass a toy safety test. ______________________________________________________________________ Therefore, we should not start requiring automatic weapons owners to pass an automatic weapons safety test. Which of the following would have to be added as a premise to the argument above, in order to turn it into a causal slippery slope argument?