Marcel's “availability” in existential psychotherapy with couples and families

Gabriel Marcel was a French, Catholic, existential philosopher who first presented the concept of human availability as a central way of strengthening the self and facilitating the experience of human freedom. In this article Marcel's ideas about availability are described, reviewed, and examined for their implications for the practice of existential psychotherapy with couples and families.     

Undecidability and intuitionistic incompleteness

Let S be a deductive system such that S-derivability (s) is arithmetic and sound with respect to structures of class K. From simple conditions on K and s, it follows constructively that the K-completeness of s implies MP(S), a form of Markov's Principle. If s is undecidable then MP(S) is independent of first-order Heyting arithmetic. Also, if s is undecidable and the S proof relation is decidable, then MP(S) is independent of second-order Heyting arithmetic, HAS. Lastly, when s is many-one complete, MP(S) implies the usual Markov's Principle MP.An immediate corollary is that the Tarski, Beth and Kripke weak completeness theorems for the negative fragment of intuitionistic predicate logic are unobtainable in HAS. Second, each of these: weak completeness for classical predicate logic, weak completeness for the negative fragment of intuitionistic predicate logic and strong completeness for sentential logic implics MP. Beth and Kripke completeness for intuitionistic predicate or sentential logic also entail MP.These results give extensions of the theorem of Gödel and Kreisel (in [4]) that completeness for pure intuitionistic predicate logic requires MP. The assumptions of Gödel and Kreisel's original proof included the Axiom of Dependent Choice and Herbrand's Theorem, no use of which is explicit in the present article.     

On maximal intermediate predicate constructive logics

We extend to the predicate frame a previous characterization of the maximal intermediate propositional constructive logics. This provides a technique to get maximal intermediate predicate constructive logics starting from suitable sets of classically valid predicate formulae we call maximal nonstandard predicate constructive logics. As an example of this technique, we exhibit two maximal intermediate predicate constructive logics, yet leaving open the problem of stating whether the two logics are distinct. Further properties of these logics will be also investigated.Presented by H. Ono     

Contrary-to-duty obligations

We investigate under what conditions contrary-to-duty (CTD) structures lacking temporal and action elements can be given a coherent reading. We argue, contrary to some recent proposals, that CTD is not an instance of defeasible reasoning, and that methods of nonmonotonic logics are inadequate since they are unable to distinguish between defeasibility and violation of primary obligations. We propose a semantic framework based on the idea that primary and CTD obligations are obligations of different kinds: a CTD obligation pertains to, or pre-supposes, a certain context in which a primary obligation is already violated. This framework is presented initially as an extension of Standard Deontic Logic (SDL), a normal modal logic of type KD, and is illustrated by application to a series of examples. The concluding section is concerned with some resemblances between CTD and defeasible reasoning. We show first that the SDL-based framework contains a flaw and must be adjusted. A discussion of possible adjustments, including an alternative treatment in terms of a preference-based semantics, reveals difficulties that are reminiscent of problems in defeasible reasoning and intensional accounts of defeasible conditionals.     

Quantum MV algebras

We introduce the notion of quantum MV algebra (QMV algebra) as a generalization of MV algebras and we show that the class of all effects of any Hilbert space gives rise to an example of such a structure. We investigate some properties of QMV algebras and we prove that QMV algebras represent non-idempotent extensions of orthomodular lattices.I should like to thank Prof. M.L. Dalla Chiara and Dr. P. Minari for many interesting comments and remarks. Daniele Mundici     

Prima facie obligation

This paper presents a nonmonotonic deontic logic based on commonsense entailment. It establishes criteria a successful account of obligation should satisfy, and develops a theory that satisfies them. The theory includes two conditional notions of prima facie obligation. One is constitutive; the other is epistemic, and follows nonmonotonically from the constitutive notion. The paper defines unconditional notions of prima facie obligation in terms of the conditional notions.     

Detachment and defeasibility in deontic logic

The purpose of the paper is to present a logical framework that allow to formalize a kind of prima facie duties, defeasible conditional duties, indefeasible conditional duties and actual (indefeasible) duties, as well as to show their logical interconnections.     

The problem of moral absolutes in the ethics of Vladimir Solov'ëv

Conclusion Moral absolutes were perceived, by Solov'?v, in a dual manner: a) from the side of content, of psychology, as when we speak of feelings, emotions, etc.; and b) under a formal aspect, as “ideas,” i.e. logically. Neither of these can be treated without relating to moral absolutes astrue, and without a rationalbelief in their truth, a truth that cannot be logically proved. In my opinion, our time has become keenly aware of the universally human value of Vladimir Solov'?v's ethics, of its humanist nature, oriented towards the everyday and the ideal tasks of man, and of the concrete direction of his philosophy of “practical idealism”.     

A comparison of multiple versus single examples of the correct stimulus on task acquisition and generalization by persons with developmental disabilities

In teaching discriminations to persons with retardation, we often presume we will improve acquisition and generalization if we use multiple examples of boththe correct and incorrect stimuli. Two experiments were conducted to test this hypothesis. In the first experiment, 7 persons with moderate retardation learned to discriminate between functional words under two conditions. In one condition, Multiple Example of S- Only,1 example of the correct stimulus (S+) and 10 examples of the incorrect stimulus (S-) were used during acquisition. In the other condition, Multiple Examples of S+ and S-,10 examples of the S+ and 10 examples of the S- were used. Results showed that the condition which presented only a single example of S+ was superior 16 times and inferior 4 times during acquisition, generalization, and maintenance. A second experiment was conducted to (a) replicate the methodology and procedures in Experiment 1 with different participants, (b) determine whether the results were replicable, and (c) obtain efficiency data. Results replicated the findings of the first experiment. The condition which presented only a single example of S+ was superior on measures of (a) trials to criterion, (b) percent correct during acquisition, and (c) minutes to criterion. On measures of generalization, the two conditions were relatively equal. Thus, the condition which presented only a single example of the correct stimulus was more efficient and was just as effective in generalization as the condition which presented multiple examples of both the S+ and S-. These surprising results were discussed in terms of stimulus control, why students performed just as well during generalization when only one example of the S+ was used, why acquisition was also poorer for this condition, and how future studies might address these points.