"An analysis of Knowledge and Valuation" by Clarence Irving Lewis,1946

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Empirical statements,describing matters of fact,
are equivalent in meaning to hypothetical statements to the effect that if one were to act in certain ways,then one would come to have expriences of a certain anticipated sort.
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An empirical statement is verified by finding out whether what is presented in experience as a result of action is what one would expect.
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A priori statements
-statements whose truth is independent of matters of fact-
are true by virtue of the meanings of their terms and the logical relations between terms.
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Value statements concerning objects are empirical statements to the effect that if one were to be concerned with the objects,one would be satisfied or pleased by them ;
value statements expressive of the value-quality of experience do not admit of error and therefor,unlike value statements concerning objects,cannot be known to be true.
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"Reason and Existenz" by Karl Jaspers,1935

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No description of Existenz is possible ;
Existenz can be clarified only by reference to concrete situations.
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Existenz is the freedom of an individual,the possibility of decision ;
because man exists in this special sense,he is that which he can become in his freedom.
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The Encompassing is that which man encounters ;
considered as Being-in-itself,
the Encompassing appears only in and through the Being-which-we-are.
-We know what confronts us only in terms of what we are because of it.-
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Reason and Existenz develop mutually and are interdependent.
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In existential communication the self first comes to full consciousness of itself as a being qualified by historicity -determination in time-,uniqueness,freedom,and communality.
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"Mind and the World-Order" by Clarence Irving Lewis,1929

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A priori truths are definitive in nature ;
they specify the real because of antecedently determined criteria of what is to be called "real".
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Empirical truth is never more than probable because descriptions of matters of fact are hypothetical propositions,pragmatic in character.
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Knowledge is the result of interpreting the sensuously given by means of a priori concepts ; thus,there is no contradiction between the relativity of knowledge -to the concepts- and the independence of the object -understood in terms of the given-.
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To know is to have reason to expect that were we to act in certain ways,
our experience would present the character we expect.
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The a priori has its origin in mind,
but its applicability is a function of the world order ;
a world which would not,relative to some interpretative act of mind,
exhibit order is practically inconceivable.
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