Cognitive synonymy: a dead parrot?

Abstract Sentences $$\varphi$$ φ and $$\psi$$ ψ are cognitive synonyms for one when they play the same role in one’s life. The notion is pervasive (Sect. 1), but elusive: it bound to be hyperintensional 2), excessive fine-graining would trivialize there reasons some coarse-graining 2.1). Conceptual limitations stand way of a natural algebra 2.2), should sensitive subject matters 2.3). A cognitively adequate individuation content may intransitive 3) due ‘dead parrot’ series: sequences sentences $$\varphi _1, \ldots , \varphi _n$$ 1 , … n where adjacent _i$$ i _{i+1}$$ + while _1$$ not 3.1). Finding an account hard: Fregean equipollence won’t do 3.2) result by Leitgeb shows that wouldn’t satisfy minimal compositionality principle 3.3). Sed contra transitivity, too 3.4). In Sect. 4, we come up with formal semantics capturing this jumble desiderata, thereby showing coherent. 5, re-assess desiderata its light.