Sometimes, as one listens to scientists vigorously defending their views, their confidence seems absolute. But deep in their hearts, they know that their views are based on probabilities and that a new piece of evidence may turn up at any time and force a major shift in their views. Although they certainly have no monopoly on hard work, their willingness to work long hours and years pursuing a problem is the mark of all good scientists. For science is hard work. Although scientific methods are as varied as science itself, there is a pattern to the way that scientists go about their work.
Scientific advances begin with observations.
A census of the members of a species in some habitat is an observation. The readings on the display of a laboratory instrument are observations. But science is more than a catalog of facts. The goal of science is to find an explanation for why the facts are as they are . Such an explanation is a hypothesis .