Hey Emmaki, I can't remember what subject you're in, but I think it's okay to acknowledge that the theory you use isn't perfect. I had an awful time trying to sort out a theoretical framework for my study, and I turned the whole debate into a paper, that basically concludes that the model I've chosen is not perfect (none of them are), but it will still allow me to make progress within the field, and will still allow the results to be applied in a practical way. Of course, you want to make it clear why you chose one theory over the others, so big it up as much as you can and point out the positives of using it, but don't worry about trying to pretend it's the perfect solution if it's not! Sometimes (as in my subject) there are no perfect solutions....! Good luck, KB