We Know More Than We Can Tell.

And The Actual Achievements Of Biology Are Explanations In Terms Of Mechanisms Founded On Physics And Chemistry, Which Is Not The Same Thing As Explanations In Terms Of Physics And Chemistry.

Of Course Language Manifests A Belief Only If We Use Its Words With The Implied Acceptance Of Their Appositeness.

I Shall Suggest, On The Contrary, That All Communication Relies, To A Noticeable Extent On Evoking Knowledge That We Cannot Tell, And That All Our Knowledge Of Mental Processes, Like Feelings Or Conscious Intellectual Activities, Is Based On A Knowledge Which We Cannot Tell.

The Amount Of Knowledge Which We Can Justify From Evidence Directly Available To Us Can Never Be Large. The Overwhelming Proportion Of Our Factual Beliefs Continue Therefore To Be Held At Second Hand Through Trusting Others, And In The Great Majority Of Cases Our Trust Is Placed In The Authority Of Comparatively Few People Of Widely Acknowledged Standing.

Our Reliance On The Validity Of A Scientific Conclusion Depends Ultimately On A Judgment Of Coherence; And As There Can Exist No Strict Criterion For Coherence, Our Judgment Of It Must Always Remain A Qualitative, Nonformal, Tacit, Personal Judgment.