The phrase "serious questions" refers to important or significant inquiries that are not meant to be taken lightly. It suggests that the topic being discussed is important and requires thoughtful consideration or response. Full definition
Not only does this raise serious questions about how the new policy will be paid for, it means that the policy as it stands will mainly benefit people on above average incomes. (socialliberal.net)
A humorous tale at times, which raises serious questions about humanity and our consideration to all people on earth. (tes.com)
It asks serious questions about our ability to enjoy things in moderation; to regulate what we watch. (premierchristianity.com)