Let us say I want to know why the sky is blue, my understanding is that I can ask you: "Why do you think the sky is blue?" regardless of whether you have thought about it before or not. It seems from the moment you hear this question you start thinking about it. Here the emphasis is really on the natural phenomenon, not on the person who is thinking about it.
On the other hand, let us say my friend told me he thinks that life exists on Mars. Then I can also ask "Why do you think life exists on Mars?" It seems to me that these two situations are different. The emphasis here is on the person, on what lead this particular person to think in a certain way.
Are there ways to slightly modify either or both questions so as to indicate the difference between these two situations?
Best Answer
Depending on context, the above question could have an almost whimsical feel to it. The questioner might not really be concerned with finding an answer, perhaps he or she is merely saying out loud a thought which struck them at that moment. If the person asking wanted a scientific explanation then a more appropriate question would be: "Why is the sky blue?" The sky is blue (or it appears to be so) is a given fact, it is not an opinion. The reason for it being blue is the question being asked.
There is a slight ambiguity in the question. Does the questioner also think there is life on Mars? Or is he or she challenging that person to justify their conviction, opinion or belief that there is life on Mars today? Not everyone upholds the opinion that there is life on that planet, many believe that some form of life may have existed in the past and some are convinced that there has never been any life on Mars. In any case, the question is clearly asking for clarification.
Alternative phrases are the following:
PRESENT EVENT
PAST EVENT