Just off the top of my head: I think both... are valid (in their own ways). I think both... have merit. I think both... hold water.

I've always thought the most effective way to convey the validity of two contradictory arguments is to show that you understand where they both come from. That way, you don't even need to say you find things right about both, because you mention aspects of each one that would appeal to the "logical" and "fact-based" parts of people, and then your audience can choose for itself. One example could be the famous "nature vs. nurture" debate, which is basically between two schools of thought that assert people are either born a certain way (nature), or they are made a certain way by their surroundings (nurture). After gathering your evidence from whatever sources that support each argument, you could say something like, "Indeed, the influence of one's environment is unavoidable, and we, as humans, are bound to adjust our behavior according to it (e.g., a boy's inclination to imitate the authoritarian male figure, a French woman learning English and losing her accent entirely after spending enough years in a homogeneous American suburb). Nevertheless, there are certain innate predilections that can drive us in any environment (e.g., the desire to procreate, the will to survive)." I just made that up, so it's probably flawed, but you know what I mean? You're showing that you understand the correct aspects of both arguments. There aren't any expressions, per se, that I tend to use, unless I am following the structure above: "Blah blah blah point A, [however/but/nevertheless/on the other side of the coin/regardless/at the same time/yet/on the other hand/still] blah blah blah point B." One more thing. If I want to show that I comprehend both theories on an issue, but I ultimately have to take a stand on one, I'll usually say something valid about the theory I disagree with, but then point out something that makes me agree with the opposing theory. So, for example: "While it is natural for any adolescent, as a result of inevitable biological triggers, to be more frequently guided by his or her emotions, the inclination to rebel, regardless, is cultivated by having something to rebel against in the first place, and thus a parent that promotes a foundation of respect, rather than fear or passivity, will, with few exceptions, raise a more mature child." I show there that I agree with parts of both theories, but ultimately I agree with one, on the whole, more than the other.

That thought did cross my mind, Bruce. Thank you so much for the comment! You made me want to put some more thought into this, and write a notenook entry here. Thank you again. x

Hi Samomoi: First, you need to identify what your criteria for knowledge is, concerning what is to be determined as "make sense" or true. You have mentioned one position as "logically reasoned". The difficulty is that phrases like "make sense" are non-specific. Thus, if logic is your criteria, as it is for Science, Law, Philosophy and Theology and other knowledge disciplines, then you must dismiss one or the other, on the basis of the Aristotelian Law of Non-Contradiction. Conflicting theories, cannot Both---Be---True, in the same context, about the same subject, and at the same time. Without identifying an objective criteria for your knowledge standard, you can simply say that everything you write and speak "makes sense". That is why Western Civilization does not operate on a Rhetorical Standard for knowledge claims. What a fascinating inquiry you have going though. Very interesting.--Warm Regards, Bruce