All You Need are Axioms
: A Defence of Deflationism via Formal Truth Theory

  • Alexander M Jones

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


My thesis presents a novel argument for deflationism about truth using
new research in formal truth theory.

In Chapter 2 I show the inadequacy of CT− as a truth theory for nonstandard models of syntax. I develop an extended T-Schema to overcome this and prove it entails non-conservativity over arithmetic. This shows a minimally adequate purely alethic theory has powerful deductive consequences. I argue, against the conservativity argument, this is a boon for deflationism. To do this, Chapter 3 provides a novel account of which theories of truth are deflationary, namely purely logical-linguistic-semantic theories of the word ‘true’. Chapter 4 then considers which formal theories of truth are deflationary and argues deflationary theories need not be proof-theoretically conservative, semantically conservative or formally logical. Instead, taking my conception of deflationism from Chapter 4, I argue that all current axiomatic theories of truth are deflationary. In Chapter 5 I develop and explore two new axiomatic theories of truth and argue for one’s adequacy as a formal theory of truth. Chapter 6 provides a new philosophical
position, deflationary alethic pluralism, which I argue shows even a simple
deflationary theory of truth can capture the philosophical and linguistic
benefits of a powerful pluralist theory of truth.

I conclude in Chapter 7 that, taken together, these results imply the adequacy of, and provide support for, deflationism about truth. This has important ramifications for those who seek truths. It tells us that theoreticians need not be concerned with metaphysical or epistemic features of truth, particularly those which could conflict with their practice. Further, philosophers using the notion of truth to phrase their theory do not incur additional commitments by doing so. With a deflationary conception of truth, troubling aspects of truth are removed from focus, leaving theoreticians free to pursue the truths of their particular domain.
Date of Award23 Jan 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorLeon Horsten (Supervisor) & Daniel Whiting (Supervisor)


  • Truth
  • Axiomatic theories of truth
  • Formal truth theories
  • Semantics
  • Logic
  • Deflationism
  • Deflationary truth

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