I'm doing an introductory undergraduate course on philosophy. I was reading an introduction to what argument is and what kinds of arguments there are when I came across this.
'Soundness: An argument is sound if it is (i) valid and (ii) has true premises. So the soundness of an argument depends on both its form (i) and its content (ii). Not all valid arguments are sound. Not all arguments with true premises and a true conclusion are sound.'
I don't understand how an argument could be unsound if it has a true premise and a true conclusion. What would an example of such an argument be?