Agreed. It's absolutely appropriate for all of those tentative words to be used in this paper. It's raising a very interesting and potentially very important n

Agreed. It's absolutely appropriate for all of those tentative words to be used in this paper. It's raising a very interesting and potentially very important notion, and that is the merit of the paper. Sometimes the merit of a paper can be the evidence that is presented, but it doesn't need to be the case. This one is a very clear call for investigation. It's also an important part of academic publishing to be very clear when evidence is lacking - part of the point of doctoral training is to train the student to not claim something is true where there isn't sufficient evidence. If you're in your final examination for your doctorate and you are asked a question that you don't know the answer to, it's absolutely appropriate to respond with "I don't know". In fact, some examiners will deliberately ask such a question to check that you will respond like that.