This sounds like a good idea for an intramural softball game at a university. The scientists can put together a team, and the historians too. We scientists might lose -- we spend all our time doing science and not practicing softball (but I cannot speak for everyone).
A scientist is someone who applies the scientific method in order to learn more about nature. You can have a look at one of our answers to the question "The Role of a Scientist" to find out more. Scientists try hard to be good citizens and good neighbors and human beings as well as being dedicated to finding out more about nature by coming up with and testing them with experiments.
A historian often (we hope usually) acts in the same way as a scientist ought to act. History is really just our model of what happened, explained as best as we know how to. Which means that it is a collection of theories and descriptions, which is really what science is all about. These theories have to be tested with the facts, and if a theory conflicts with some kind of observation, it must be discarded and new theories sought. New explanations that are bolstered by more evidence win out over old ones, and sometimes history gets rewritten as more things are found out. Archaeology provides a great example of how historians can discover new material which can overturn old ideas and bring new ones into prominence.
Many geologists are really on the boundary between being historians and being like other scientists, in that they explore the natural world and come up with explanations about the history of the land masses and rocks.
One thing that scientists are renowned for is the care with which most of them try to study the biases and distortions of their equipment or their own personal biases. In the disciplines of physics, it is usually pretty cut and dried how a piece of apparatus can give you the wrong answer, but still in order to get proper measurements and assign the right uncertainties to them, we have to find all the subtle little biases (even the ones which are difficult or impossible to measure) and estimate how wrong we can be. Historians are getting much better these days at examining their own biases, but sometimes more of their claims are impossible to prove conclusively (history cannot be repeated under controlled conditions, usually, in order to find out what really happened a long time ago, while physics experiments can always be redone). This is a recent development -- historians before the 20th century used to include all kinds of cultural biases in their works. Sometimes reading an old historical account of an event or time period which was even older contained more information about the time which the account was written, than what was written about. We hope that by applying the scientific method of confronting hypotheses with observations, the historical record can be made more reliable.
A funny quote:
"History doesnít repeat itself -- historians merely repeat each other." (attributed to Winston Churchill)
P.s. Iím not sure that there has been enormous progress in removing biases from historical accounts. History is just so unclear and so close to the things people argue about passionately that itís hard to be completely objective. Thucydides wrote a rather objective account of the war between Athens and Sparta some 2400 years ago, yet many modern histories of wars look very biased, especially to people from countries other than the authorís.
(republished on 07/13/06)