Is the following statement valid or invalid?All forms of cheating are ethically wrong. Plagiarism is a form of cheating. Therefore, plagiarism is...

A philosophical argument is considered
valid if the truth of the premises logically create a truthful
conclusion.  In this way, an argument based on false premises can still be considered
valid.

On the other hand, an argument can only be
considered sound if all of the premises are actually true and also
logically lead to a truthful conclusion.

On first reading,
this argument sounds both valid and sound.  The only questionable part of the above
statement is the first premise, "All forms of cheating are ethically wrong."  The
question "What is ethical?" could be considered subjective, which makes this a valid and
sound argument based on the presumption that cheating is always
unethical.

Consider that there might be time where
cheating, say, a corrupt system for example, might result in a more
ethical situation than the system in place.  In such a case, the first premise of this
statement could be considered falsifiable.