Final answer:
It is a logical fallacy to say that it is illegal to own just one guinea pig because a lawyer in Switzerland says so.
Step-by-step explanation:
Yes, it is a logical fallacy to say that it is illegal to own just one guinea pig because a lawyer in Switzerland says so. This is a fallacy known as an appeal to authority, where the claim is considered true simply because it is made by an authority figure. In this case, the lawyer's opinion does not provide a logical basis for the claim that owning one guinea pig is illegal.