Scientific Progress Consists In The Development Of

All Interpretations Made By A Scientist Are Hypotheses, And All Hypotheses Are Tentative. They Must Forever Be Tested And They Must Be Revised If Found To Be Unsatisfactory. Hence, A Change Of Mind In A Scientist, And Particularly In A Great Scientist, Is Not Only Not A Sign Of Weakness But Rather Evidence For Continuing Attention To The Respective Problem And An Ability To Test The Hypothesis Again And Again.

The Most Consequential Change In Man's View Of The World, Of Living Nature And Of Himself Came With The Introduction, Over A Period Of Some 100 Years Beginning Only In The 18th Century, Of The Idea Of Change Itself, Of Change Over Periods Of Time: In A Word, Of Evolution.

Scientific Progress Consists In The Development Of New Concepts.

To Take An Unequivocal Stand, It Seems To Me, Is Of Greater Heuristic Value And Far More Likely To Stimulate Constructive Criticism Than To Evade The Issue.

Biology Can Be Divided Into The Study Of Proximate Causes, The Study Of The Physiological Sciences (broadly Conceived), And Into The Study Of Ultimate (evolutionary) Causes, The Subject Of Natural History.