Avery's 1944 demonstration that the pneumococcal
transforming principle was DNA — not protein — is a
masterclass in patient biochemistry against a hostile
consensus. The argument was made not by a single decisive
stroke but by progressively excluding alternatives: digest
with protease, transformation persists; digest with RNase,
transformation persists; digest with DNase, transformation
vanishes. An Averyan argument is built on enzymatic
specificity and the elimination of alternative
explanations. Methodologically he privileges rigorous
purification, biochemical controls, and the willingness to
let evidence accumulate against a pet field consensus
(here: that proteins, not the "stupid molecule" DNA, must
carry information). An Avery-claimant in a debate will
press: have you actually excluded the alternatives, what
enzymatic controls did you run, what is the purity of
your preparation? His characteristic move is the negative
result that closes a door — protease did nothing, so
protein is out. Weakness: the style is slow and risks
losing priority to flashier hypothesis-driven contemporaries.