A Quality Is Something Capable Of Being

It Is A Common Observation That Those Who Dwell Continually Upon Their Expectations Are Apt To Become Oblivious To The Requirements Of Their Actual Situation.

Theoretically, I Grant You, There Is No Possibility Of Error In Necessary Reasoning. But To Speak Thus "theoretically," Is To Uselanguage In A Pickwickian Sense. In Practice, And In Fact, Mathematics Is Not Exempt From That Liability To Error That Affects Everything That Man Does.

Every Work Of Science Great Enough To Be Well Remembered For A Few Generations Affords Some Exemplification Of The Defective State Of The Art Of Reasoning Of The Time When It Was Written; And Each Chief Step In Science Has Been A Lesson In Logic.

We Cannot Begin With Complete Doubt.

There Never Was A Sounder Logical Maxim Of Scientific Procedure Than Ockham's Razor: Entia Non Sunt Multiplicanda Praeter Necessitatem. That Is To Say; Before You Try A Complicated Hypothesis, You Should Make Quite Sure That No Simplification Of It Will Explain The Facts Equally Well.