One of the characteristics that distinguish conservative, liberal and radical philosophies is their opinion on political reform.
Conservatives, as the name indicates, want to "conserve" traditions and institutions. They believe that change should be slow, and that institutions that have traditionally worked have extra value because of their longevity.
Liberals, on the other hand, believe in the idea of progress and self-improvement. They believe that, if an institution is not efficient enough, society benefits from replacing it. They also defend the freedom of individuals to push for change, even if it goes against social institutions and traditions.
Finally, radicals favor extreme and deep reform. They see little value in tradition, and believe that extreme change is the only answer for problems that run deep or are particularly pervasive.