History, whether we recognize it or not, is advancing. This belief is grounded on optimism that certain changes are undeniably forthcoming and that observable, objective conditions in society simply render such developments to proceed, regardless of deliberate opposition posed by the beneficiaries and self-same purveyors of the exploitative status quo. The instigators of such encumberance to 'progress' are aptly identified as 'reactionaries.' Not only are they conservative, but actively campaign and work (although, in vain) to thwart, contain and at best delay the institution of these legitimate and called for changes. The opposite force would naturally be the progressives -- the forward thinkers. Those who embrace positive, deep-going reforms and actively work to attain progress -- generally recognized as the elimination of inequity and inequality. Those who dare challenge and struggle against the unjust establishment that consciously reacts (and oftentimes viciously endeavors) to prevent human development from realizing its fullest potential in order to protect the interests of an elite few. (By the way, I'm from the Philippines. I'm not really aspiring for the prize. Just wanted to share my view. More power!)

Keywords from above, used in other answers: