ISSN:
1572-8730
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mathematics
,
Philosophy
Notes:
Abstract In their book Entailment, Anderson and Belnap investigate the consequences of defining ‘Lp’ (it is necessary that p) in system E as (p→p)→p. Since not all theorems are equivalent in E, this raises the question of whether there are reasonable alternative definitions of necessity in E. In this paper, it is shown that a definition of necessity in E satisfies the conditions {⊢ E Lp→p, ⊢EL(p→q)→(Lp→Lq), ⊢E p→Lp} if and only if its has the form C 1→.C2→ ...→. Cn→p, where each C iis equivalent in E to either p→p or ((p→p)→p)→p.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00370435