Cognitive synonymy: a dead parrot?

Franz Berto*, Levin Hornischer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
6 Downloads (Pure)


Sentences φ and ψ are cognitive synonyms for one when they play the same role in one’s cognitive life. The notion is pervasive (Sect. 1), but elusive: it is bound to be hyperintensional (Sect. 2), but excessive fine-graining would trivialize it and there are reasons for some coarse-graining (Sect. 2.1). Conceptual limitations stand in the way of a natural algebra (Sect. 2.2), and it should be sensitive to subject matters (Sect. 2.3). A cognitively adequate individuation of content may be intransitive (Sect. 3) due to ‘dead parrot’ series: sequences of sentences φ1,…,φn where adjacent φi and φi+1 are cognitive synonyms while φ1 and φn are not (Sect. 3.1). Finding an intransitive account is hard: Fregean equipollence won’t do (Sect. 3.2) and a result by Leitgeb shows that it wouldn’t satisfy a minimal compositionality principle (Sect. 3.3). Sed contra, there are reasons for transitivity, too (Sect. 3.4). In Sect. 4, we come up with a formal semantics capturing this jumble of desiderata, thereby showing that the notion is coherent. In Sect. 5, we re-assess the desiderata in its light.
Original languageEnglish
Pages (from-to)2727-2752
Number of pages26
JournalPhilosophical Studies
Early online date17 Jul 2023
Publication statusPublished - 1 Sept 2023


  • Aboutness
  • Subject matter
  • Hyperintensionality
  • Synonymy
  • Defeasible reasoning
  • Cognitive content
  • Leitgeb impossibility result


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