Francisco Martin

Este artículo emprende un cotejo de textos pertenecientes a tres periodos diferentes del pensamiento de Habermas y defiende que existe una conexión genealógica entre la concepción de la racionalidad procedimental con las ideas de la esfera pública burguesa y de la situación ideal de habla. Además de examinar el contenido normativo de la racionalidad procedimental asentado en las “reglas de la razón”, el artículo explora algunas de las implicaciones de la dimensión pública de las idealizaciones inevitables y contrafácticas de los discursos racionales.

A well known theorem proved by J. Paris and H. Friedman states that BΣn +1 is a Πn +2-conservative extension of IΣn. In this paper, as a continuation of our previous work on collection schemes for Δn +1-formulas, we study a general version of this theorem and characterize theories T such that T + BΣn +1 is a Πn +2-conservative extension of T. We prove that this conservativeness property is equivalent to a model-theoretic property relating Πn-envelopes and Πn-indicators for T. The analysis of Σn +1-collection we develop here is also applied to Σn +1-induction using Parsons' conservativeness theorem instead of Friedman-Paris' theorem.As a corollary, our work provides new model-theoretic proofs of two theorems of R. Kaye, J. Paris and C. Dimitracopoulos : BΣn +1 and IΣn +1 are Σn +3-conservative extensions of their parameter free versions, BΣ–n +1 and IΣ–n +1.

By a theorem of R. Kaye, J. Paris and C. Dimitracopoulos, the class of the Πn+1-sentences true in the standard model is the only consistent Πn+1-theory which extends the scheme of induction for parameter free Πn+1-formulas. Motivated by this result, we present a systematic study of extensions of bounded quantifier complexity of fragments of first-order Peano Arithmetic. Here, we improve that result and show that this property describes a general phenomenon valid for parameter free schemes. As a consequence, we obtain results on the quantifier complexity, finite axiomatizability and relative strength of schemes for Δn+1-formulas.

Hilary Putnam y Jürgen Habermas comparten la convicción de que la finitud de la mente humana es una virtud y no una deficiencia. En este trabajo analizo esta convicción filosófica de ambos mediante la comparación de sus formas de renunciar a la concepción pragmática de la verdad y con una revisión de debate en torno a la objetividad de los valores y normas. Hilary Putnam and Jürgen Habermas share the conviction that the finitude of the human mind is a virtue and not a shortcoming. In this paper I track this shared philosophical conviction by comparing their ways of withdrawing the pragmatist conception of truth and by reviewing their debate on the objectivity of values and norms.