Neologicist Foundations: Inconsistent Abstraction Principles and Part-Whole
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Paolo Mancosu
Abstract
Neologicism emerges in the contemporary debate in philosophy of mathematics with Wright’s book Frege’s Conception of Numbers as Objects (1983).Wright’s project was to show the viability of a philosophy of mathematics that could preserve the key tenets of Frege’s approach, namely the idea that arithmetical knowledge is analytic. The key result was the detailed reconstruction of how to derive, within second order logic, the basic axioms of second order arithmetic from Hume’s Principle HP ∀X, Y(#X = #Y ↔ X ≅ Y) (and definitions). This has led to a detailed scrutiny of so-called abstraction principles, of which Basic Law V BLV ∀X, Y(∂X = ∂Y ↔ ∀x (X(x) ↔ Y(x))) and HP are the two most famous instances. As is well known, Russell proved that BLV is inconsistent. BLV has been the only example of an abstraction principle from (monadic) concepts to objects giving rise to inconsistency, thereby making it appear as a sort of monster in an otherwise regular universe of abstraction principles free from this pathology. We show that BLV is part of a family of inconsistent abstractions. The main result is a theorem to the effect that second-order logic formally refutes the existence of any function F that sends concepts into objects and satisfies a ‘part-whole’ relation. In addition, we study other properties of abstraction principles that lead to formal refutability in second-order logic.
Abstract
Neologicism emerges in the contemporary debate in philosophy of mathematics with Wright’s book Frege’s Conception of Numbers as Objects (1983).Wright’s project was to show the viability of a philosophy of mathematics that could preserve the key tenets of Frege’s approach, namely the idea that arithmetical knowledge is analytic. The key result was the detailed reconstruction of how to derive, within second order logic, the basic axioms of second order arithmetic from Hume’s Principle HP ∀X, Y(#X = #Y ↔ X ≅ Y) (and definitions). This has led to a detailed scrutiny of so-called abstraction principles, of which Basic Law V BLV ∀X, Y(∂X = ∂Y ↔ ∀x (X(x) ↔ Y(x))) and HP are the two most famous instances. As is well known, Russell proved that BLV is inconsistent. BLV has been the only example of an abstraction principle from (monadic) concepts to objects giving rise to inconsistency, thereby making it appear as a sort of monster in an otherwise regular universe of abstraction principles free from this pathology. We show that BLV is part of a family of inconsistent abstractions. The main result is a theorem to the effect that second-order logic formally refutes the existence of any function F that sends concepts into objects and satisfies a ‘part-whole’ relation. In addition, we study other properties of abstraction principles that lead to formal refutability in second-order logic.
Chapters in this book
- Frontmatter I
- Contents V
- Preface IX
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Part I: Philosophy of Logic
- Link’s Revenge: A Case Study in Natural Language Mereology 3
- Universal Translatability: An Optimality- Based Justification of (Classical) Logic 37
- Invariance and Necessity 55
- Translations Between Logics: A Survey 71
- On the Relation of Logic to Metalogic 91
- Free Logic and the Quantified Argument Calculus 105
- Dependencies Between Quantifiers Vs. Dependencies Between Variables 117
- Three Types and Traditions of Logic: Syllogistic, Calculus and Predicate Logic 133
- Truth, Paradox, and the Procedural Conception of Fregean Sense 153
- Wittgenstein and Frege on Assertion 169
- Assertions and Their Justification: Demonstration and Self-Evidence 183
- Surprises in Logic: When Dynamic Formality Meets Interactive Compositionality 197
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Part II: Philosophy of Mathematics
- Neologicist Foundations: Inconsistent Abstraction Principles and Part-Whole 215
- What Hilbert and Bernays Meant by “Finitism” 249
- Wittgenstein and Turing 263
- Remarks on Two Papers of Paul Bernays 297
- The Significance of the Curry-Howard Isomorphism 313
- Reductions of Mathematics: Foundation or Horizon? 327
- What Are the Axioms for Numbers and Who Invented Them? 343
-
Part III: Wittgenstein
- Following a Rule: Waismann’s Variation 359
- Propositions in Wittgenstein and Ramsey 375
- An Unexpected Feature of Classical Propositional Logic in the Tractatus 385
- Ontology in Tractatus Logico-Philosophicus: A Topological Approach 397
- Adding 4.0241 to TLP 415
- Understanding Wittgenstein’s Wood Sellers 429
- On the Infinite, In-Potentia: Discovery of the Hidden Revision of Philosophical Investigations and Its Relation to TS 209 Through the Eyes of Wittgensteinian Mathematics 441
- Incomplete Pictures and Specific Forms: Wittgenstein Around 1930 457
- „Man kann die Menschen nicht zum Guten führen“ – Zur Logik des moralischen Urteils bei Wittgenstein und Hegel 473
- Der Status mathematischer und religiöser Sätze bei Wittgenstein 485
- Gutes Sehen 499
- Wittgenstein’s Conjecture 515
- Index of Names 535
- Index of Subjects 539
Chapters in this book
- Frontmatter I
- Contents V
- Preface IX
-
Part I: Philosophy of Logic
- Link’s Revenge: A Case Study in Natural Language Mereology 3
- Universal Translatability: An Optimality- Based Justification of (Classical) Logic 37
- Invariance and Necessity 55
- Translations Between Logics: A Survey 71
- On the Relation of Logic to Metalogic 91
- Free Logic and the Quantified Argument Calculus 105
- Dependencies Between Quantifiers Vs. Dependencies Between Variables 117
- Three Types and Traditions of Logic: Syllogistic, Calculus and Predicate Logic 133
- Truth, Paradox, and the Procedural Conception of Fregean Sense 153
- Wittgenstein and Frege on Assertion 169
- Assertions and Their Justification: Demonstration and Self-Evidence 183
- Surprises in Logic: When Dynamic Formality Meets Interactive Compositionality 197
-
Part II: Philosophy of Mathematics
- Neologicist Foundations: Inconsistent Abstraction Principles and Part-Whole 215
- What Hilbert and Bernays Meant by “Finitism” 249
- Wittgenstein and Turing 263
- Remarks on Two Papers of Paul Bernays 297
- The Significance of the Curry-Howard Isomorphism 313
- Reductions of Mathematics: Foundation or Horizon? 327
- What Are the Axioms for Numbers and Who Invented Them? 343
-
Part III: Wittgenstein
- Following a Rule: Waismann’s Variation 359
- Propositions in Wittgenstein and Ramsey 375
- An Unexpected Feature of Classical Propositional Logic in the Tractatus 385
- Ontology in Tractatus Logico-Philosophicus: A Topological Approach 397
- Adding 4.0241 to TLP 415
- Understanding Wittgenstein’s Wood Sellers 429
- On the Infinite, In-Potentia: Discovery of the Hidden Revision of Philosophical Investigations and Its Relation to TS 209 Through the Eyes of Wittgensteinian Mathematics 441
- Incomplete Pictures and Specific Forms: Wittgenstein Around 1930 457
- „Man kann die Menschen nicht zum Guten führen“ – Zur Logik des moralischen Urteils bei Wittgenstein und Hegel 473
- Der Status mathematischer und religiöser Sätze bei Wittgenstein 485
- Gutes Sehen 499
- Wittgenstein’s Conjecture 515
- Index of Names 535
- Index of Subjects 539