Husserl I. The Realm of Ideas Philosophy 157 ©2002, G. J. Mattey

Empiricism All substantive human knowledge is based on the input of the senses Reason by itself discovers only non- substantive connections between concepts Reason applied to sensory input yields generalizations which are only probable

Psychologism A form of empiricism Adopted by John Stuart Mill, as well as a number of German philosophers of the late nineteenth century Basic thesis: the “laws” of logic are only empirical generalizations based on observation of the workings of the human mind

Basic Argument for Psychologism 1.Inference from premises to conclusion is a psychological process. 2.Laws governing psychological processes are psychological laws. 3.Psychological laws are empirical generalizations. 4.So, laws governing inferences are empirical generalizations.

Kantian Response Psychological laws are descriptive, while laws of logic are normative Descriptive laws tell us what is, while normative laws tell us about what ought to be Analogy: basing moral laws on observation of human behavior alone

Rebuttal by Psychologism The purpose of logic is to further the goals of the mind How best to further these goals depends on how the mind works The workings of the mind are governed by psychological laws

Circularity Response Psychology itself depends on laws of logic If laws of logic are based on psychology, then they are based on themselves Laws of logic based on themselves are circular

Rebuttal by Psychologism Logic applies to itself, and so there is an apparent circularity: logic establishes the validity of the rules it presupposes But it does not do so by using laws of logic as premises in arguments establishing the validity of arguments Logic is used as a standard of valid arguments instead

The Middle Way Both sides have grasped part of the truth about the laws of logic Psychologism correctly recognizes that logic is used as a tool to regulate inference, which is a psychological process But it mistakenly takes this process to be the subject-matter of logic The real subject-matter of logic is an ideal realm

The Normativity of Logic A law of logic: no proposition is both true and false This law has no normative content: it says nothing about what one ought to believe But its meaning gives it an “intrinsic prerogative in the regulation of our thought”

The “Circularity” of Logic The proposition that no proposition is both true and false applies to itself It is not both true and false But this self-reference is not harmful, but “an obvious truism”

What Logic is About The laws of thought describe an ideal realm, just as with mathematics Populating the ideal realm are “Truth, Proposition, Subject, Object, Property, Ground and Consequent, Relation and Relatum, etc.” Truths regarding this realm are self-evident, involving a “primal givenness”

Phenomenology True and false judgments have the same phenomenological content The content of the judgment is what is “meant” by it There is a separate “experience of truth” The truth is given in the agreement between what is meant and what is present (the ideal objects, in the case of logic)

Logic and Evidence A judgment is true if and only if it is inwardly evident Being inwardly evident can be construed as a psychological state. But truth and inward evidence are only materially equivalent, and concern different subject-matters The law of non-contradiction governs what can be inwardly evident But the realm of the logically possible may outstrip the abilities of the human mind