We ended last time on Kant’s two categories of knowledge, the a priori and the a posteriori.  The concept of a posteriori knowledge requires further refining, especially distinguishing ‘authentic’ knowledge from mere opinion. Science and investigative history count as the former even though they are corrigible and mutable, whereas individual beliefs and personal taste do not. Since reality usually refers to the ‘knowable’ independent of the ‘knower,’ it follows that knowledge must be public, not private, that is, nothing knowable by one person alone can have the status of knowledge.7 Moreover, authentic knowledge is the result of directed experimental operations and investigation processed through disciplined reason.

But what is the criterion of truth? In the course of human history, philosophers have identified three theories of truth:

1.    Correspondence – truth is what corresponds to reality or fact (the common idea of truth).

2.   Coherence – truth is that which coheres with other truths or beliefs (includes convergence).

3.   Pragmatism – truth is that which can be used to guide behavior; that is ‘what works.’

Since empirical knowledge is never certain and always amendable, the most prudent course is to use all three when possible, rather than choose one, in order to achieve the greatest confidence possible of any statement.8

Finally there is the question of how to circumscribe a corpus of truth and authentic knowledge in a world of assumptions, misconceptions, error, prejudice, and unjustified opinion. It begins with the recognition that the validity of a belief is not correlated to the passion of its adherents. The philosophical tool of doubt – the greatest legacy of the ancient skeptics – is the prelude to whatever truth and certainty is possible for humans. From there investigation may uncover relevant evidence and reason may offer cogent arguments, that an open dialectic or debate filter into knowledge of the highest confidence. While still potentially flawed, such information meets an acceptable standard for guiding ethical behavior.

These last two posts contain an implicit assumption, that knowledge, truth, and certainty are purely objective. Next time we will blur the picture by considering subjective features of truth.


1Webster’s New Universal Unabridged Dictionary, Barnes & Noble, Inc. 2003. ISBN 0-7607-4975-2, page 339, definitions 1 and 4.

2Edwards, Paul (editor), The Encyclopedia of Philosophy. Macmillan Publishing Co., Inc. & The Free Press, 1972.   Volume 2, page 67.

3Webster’s New Universal Unabridged Dictionary, Barnes & Noble, Inc. 2003. ISBN 0-7607-4975-2, pages 2029 and 2031

4Ibid. Page 1064, definitions 1 and 7.

5Adler, Mortimer J., Adler’s Philosophical Dictionary. Simon and Schuster, New York, 1996. ISBN 0-684-80360-7, page 53.

6Adler, Mortimer J., Ten Philosophical Mistakes, Macmillan Publishing Company, 1985. ISBN 0-02-064120-6, page 83.

7Ibid. Pages 89-90.

8See my post Current Reading – Truth this site dated 11/16/2018.

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