Do Atoms Exist?

Most of us in this day and age consider our belief in atoms as old news in the ontology of the universe.  Why would we ever question their existence?  Yet if you think carefully about the history of science, the principles of induction, and the practical evidence we have available to us, we ought to wonder for just a moment: Why do we believe that atoms exist?  More specifically, what evidence do you have--your average educated person--for belief in the existence of atoms?

Imagine that you’re back in 1860, at the first international Karlsruhe Congress.  The topic then was whether in fact atoms existed or not.  The players: Mendeleev, Meyer, and a series of other big name scientists in the history of chemistry.  During this time, you have to remember, chemistry, along with many of the other sciences, was in a state of complete transition.  Most chemists believed in atoms and molecules, of course, but nobody could agree about their formulation or could give rational justification for their existence.  Consider for example, that in 1860 chemists didn’t even agree about the molecular formula of water, with many leading chemists believing at the time that water’s molecular formula was OH, and not H2O.


So seriously, why do we believe that atoms exist?  Let’s think about this.  Why do you believe that atoms exist?