As a student of the sciences, mostly physics and recently medicine, I often will get caught in discussions of 'what is science?' as in a recent lab class. I often resist engaging in these because I feel they too often are trying to promote idealized views of this particular human endeavor. The humanity of the enterprise is forgotten in trying to give it good PR. Most recently I did have one thought on the subject that seemed of value though: science is one expression of the curiosity of mankind (and remember man in this context is gender neutral).
We have an interesting relationship with curiosity. The most well known phrase in regards to the subject is, "Curiosity killed the cat." I like to use the snappy rejoinder, "Well we better try to satisfy curiosity before that psycho goes off killing small animals to get their jollies then," but I recognize that the implication the phrase carries is to take caution with exploration and intuition. As should be obvious to the reader at this point I don't agree with this mentality, but that said it's never wise to throw caution to the wind entirely and we should certainly ensure that our actions properly reflect the correct balance of our desire to know something and other desires, such as comfort, safety, and community.
I still think that on balance curiosity is a virtue. I believe in the freedom of information, an understandable order and structure underlying the universe at large, and that challenges to one's thoughts and beliefs will eventually improve them if faced head on and not ignored. Curiosity lets us promote and explore these things. Consider what the opposite of curiosity might be. A quick look in the thesaurus brings up disinterest, indifference, perhaps even apathy. Does anyone really want to be with people or build a society with these qualities?
Science is one way in which we express our curiosity. It's perhaps the simplest, being based on straightforward observation of a community. Laws and theories are only useful in as much they can make verifiable predictions and only believable in as much as they are supported by data and experiment. This does make science somewhat limited in scope as most will recognize that there exist things that simply can't be proven one way or the other, but the pragmatic and skeptical mentality is a powerful tool for any thinker.
Science is of course a human enterprise, though. This expression of our curiosity is subject to the same forces that might make a desire for self improvement into greed or a longing for love and community into exclusion. Having guiding principles in a great human venture never means we follow them perfectly, or if it does it probably means we're losing sight of other virtues. The guiding virtues of science - observation, falsifiability and testability, and of course curiosity - will indeed help us in our endeavors to become virtuous.
