## Deviant Logic: Some Philosophical Issues |

### What people are saying - Write a review

Review of Haack, Deviant Logic, by Randal W. Samstag

Deviant Logic is based on work Susan Haack completed for a PhD dissertation at Cambridge University. The book was published by Cambridge University Press in 1974. It is a brave book in that the author provides penetrating critiques of some of the most cherished doctrines of the most prominent philosophers of logic of the previous generation: Quine, Putnam, Dummett, Popper, and Lukasiewicz. While recommending what she calls a ‘radical’ approach to non-classical logics, in the end she opts for ‘classical logic’ as the logic which best satisfies her pragmatist criteria of simplicity and economy.

While her book, as suggested by the title, considers alternatives to what she calls ‘classical logic,’ she nowhere in the body of the text says exactly what she means by ‘classical logic.’ In an appendix she provides a (very handy) semantic summary of a series of logics. This appendix provides matrices which define the truth tables for the various logical connectives in each system: negation, conjunction, disjunction, implication, and identity. Here she presents “2-valued (‘classical’) logic” as the first system considered. But for all of her attempts at clarity, she leaves the system that she is defending otherwise un-defined. It is safe to assume that what she has in mind is primarily bivalence (which she abbreviates to ‘PB’ for the principle of bivalence), but that she also includes here Aristotle’s laws of (non-)contradiction (LNC), excluded middle (LEM), and identity, in addition to the truth values for the connectives given in the appendix.

The introductory chapter sets out her goals: to establish the senses in which there could be alternative logics to bivalent logic and to systematically review the plausibility of these alternatives. The alternatives considered include: intuitionist logic, Post’s multi-valued logic, minimal logic, Lukasiewicz’s many-valued logic, van Frassen’s propositional languages, and quantum logics. She also considers systems which supplement classical logic: Lewis’s modal logic, epistemic logic, deontic logic, and tense logic. Since the book reviews only logics proposed up to the decade of the 1960s, it does not consider some logics which have become seriously considered in the last 40 years: this includes the general category of paraconsistent logics including the dialetheism of Graham Priest, relevant logic, or fuzzy logic. The latter are considered in papers appended to a subsequent edition of Deviant Logic, but the current review considers only the original text. Given what has come afterwards, her work becomes even more important in being one of the first systematic attempts to address the general question of rivals to standard bivalent logic in a clear and rigorous manner.

The first of the giants whom Haack takes on is Quine. In the first chapter she considers Quine’s argument that alternative logics are not really rivals to classical logic at all because their apparent inconsistency can be explained as involving a change of meaning of the logical constants. This argument of Quine’s derives from his famous indeterminacy theory of translation. Haack characterizes this as:

QIT: Alternative, and mutually incompatible, translations may conform to all data concerning dispositions to speaker’s behavior.

She evaluates three theses that she finds in Quine:

1) There is inductive uncertainty in the translation of even observation sentences

2) There is radical uncertainty in the translation of words and phrases

3) There is radical uncertainty in the translation of theoretical sentences

Her argument, found in section 3 of Chapter 1, accuses Quine of circularity. When Quine says that he is just trying to “save the obvious” by retaining bivalence she responds that this is obvious only if one assumes bivalent logic to begin with. Much the same response could be given to several of her own arguments against the plausibility of alternative logics considered in her book.

#### Review: Deviant Logic: Some Philosophical Issues

User Review - Scepticos - GoodreadsDeviant Logic is based on the work Susan Haack completed for a PhD dissertation at Cambridge University. The book was published by Cambridge University Press in 1974. It is a brave book that provides ... Read full review

### Contents

Reasons for Deviance | 25 |

Deviance and the theory of truth | 47 |

Part | 73 |

Intuitionism | 91 |

Vagueness | 109 |

Singular terms and existence | 126 |

Quantum mechanics | 148 |

Appendix | 168 |

178 | |

187 | |