Good Tests Kill Flawed Theories;

[great Scientists] Are Men Of Bold Ideas, But Highly Critical Of Their Own Ideas: They Try To Find Whether Their Ideas Are Right By Trying First To Find Whether They Are Not Perhaps Wrong. They Work With Bold Conjectures And Severe Attempts At Refuting Their Own Conjectures.

The Growth Of Our Knowledge Is The Result Of A Process Closely Resembling What Darwin Called 'natural Selection'; That Is, The Natural Selection Of Hypotheses: Our Knowledge Consists, At Every Moment, Of Those Hypotheses Which Have Shown Their (comparative) Fitness By Surviving So Far In Their Struggle For Existence, A Competitive Struggle Which Eliminates Those Hypotheses Which Are Unfit.

Optimism Is A Duty. The Future Is Open. It Is Not Predetermined. No One Can Predict It, Except By Chance. We All Contribute To Determining It By What We Do. We Are All Equally Responsible For Its Success.

We Do Not Choose Political Freedom Because It Promises Us This Or That. We Choose It Because It Makes Possible The Only Dignified Form Of Human Coexistence, The Only Form In Which We Can Be Fully Responsible For Ourselves. Whether We Realize Its Possibilities Depends On All Kinds Of Things — And Above All On Ourselves.

Is The World Ruled By Strict Laws Or Not? This Question I Regard As Metaphysical. The Laws We Find Are Always Hypotheses; Which Means That They May Always Be Superseded, And That They May Possibly Be Deduced From Probability Estimates. Yet Denying Causality Would Be The Same As Attempting To Persuade The Theorist To Give Up His Search; And That Such An Attempt Cannot Be Backed By Anything Like A Proof.