Taking the life of another human being is murder.
Murder is a strong word, a word that appears to have fundamental meaning for most people, but there are also many exceptions to murder that are fairly popular in society. These exceptions are by no means universal; additionally, it is rare that anyone person would agree to all of the exceptions simultaneously. The point is that many, if not most major premises are "universal" in name only. There are almost always disagreements about how to define concepts, and crafting a practical sentence that all participants agree upon to begin an argument is fundamentally impossible.
This map shows the many exceptions there are to the claim that "Taking the life of another human being is murder." The exceptions are represented in orange, and the claim is in green (if you are reading these words, then you are 'on' the claim). The syllogism does not have a mechanism to account for exceptions to the rule, which is one reason Stephen Toulmin felt a need to develop a model than included such a mechanism.