We Cannot Begin With Complete Doubt.

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.

Unless Man Have A Natural Bent In Accordance With Nature's, He Has No Chance Of Understanding Nature At All.

Theology, I Am Persuaded, Derives Its Initial Impulse From A Religious Wavering; For There Is Quite As Much, Or More, That Is Mysterious And Calculated To Awaken Scientific Curiosity In The Intercourse With God, And It [is] A Problem Quite Analogous To That Of Theology.

Mathematics Is Purely Hypothetical: It Produces Nothing But Conditional Propositions.

It Has Often Been Argued That Absolute Scepticism Is Self-contradictory; But This Is A Mistake: And Even If It Were Not So, It Would Be No Argument Against The Absolute Sceptic, Inasmuch As He Does Not Admit That No Contradictory Propositions Are True. Indeed, It Would Be Impossible To Move Such A Man, For His Scepticism Consists In Considering Every Argument And Never Deciding Upon Its Validity; He Would, Therefore, Act In This Way In Reference To The Arguments Brought Against Him.