[raverbashing]

> All one need do is demonstrate that DNA is not the source of heredity

Oh, I'm not saying DNA isn't the source of heredity. I'm saying that there are other smaller factors. (you can google them). Heredity in the strict sense, yes, it's DNA, in the broader sense, well, you can have two different fenotypes with the same genotype.

> There was a debate about whether light was a wave or a particle -- evidence supported both views.

Not before the 20th century, diffraction of light (amongst others) firmly put it as a wave. http://en.wikipedia.org/wiki/Light#Wave_theory

And the wave theory of light is still widely used (when it's applicable of course).

[lutusp]

>> There was a debate about whether light was a wave or a particle -- evidence supported both views.

> Not before the 20th century,

Yes before the 20th century. I refer you to the debate between Newton and Huygens as well as Hooke, his contemporaries with respect to these ideas.

http://www.studyphysics.ca/newnotes/20/unit04_light/chp1719_...

Such debates persisted from then until the shaping of quantum theory.