Lorenzo Magnani

It is well known that the computational complexity of propositional knowledge base revision is at the second level of polynomial hierarchy. A way to solve this kind of problems is to introduce approximate algorithms. In this paper, an approximate approach is introduced for belief change. Operators, which satisfy the AGM rational postulates, are defined to change belief sets or belief bases. Furthermore, approximate algorithms to implement the revision of finite belief bases are presented. The time complexities of the approximate algorithms shown in this paper are at lower level than the time complexities of the existed approaches in literatures, although they may not generate the optimal solution, and this is meaningful from the theoretical point of view.

In this paper we show how some reasoning, though fallacious, can appear to be attractive and useful for beings-like-us. Although they do not provide conclusive evidence to support or reject a certain claim the way scientific statements do, they tell us something interesting about how humans build up their arguments and reasons. First of all, we will consider and investigate three main types of fallacies: argumentum ad hominem, argumentum ad verecundiam, and argumentum ad populum. These three fallacies are traditionally considered as examples of a broader category called ignoratio elenchi. Secondly, we show how people who commit these fallacies rely on information about other human beings in their reasoning. That is, they do not follow certain logical procedures that eventually lead them to correct conclusions. But they simply make use of others as social characters. For example, being an authority, being an expert, being part of a class, etc., become the substitutes for more direct evidence to support a certain claim or to make an argument more appealing.

En el presente artículo se sostiene que, a través de la tecnología, las personas podemos simplificar y resolver tareas morales incluso en presencia de información incompleta o de una capacidad insuficiente para la acción moral. Muchas cosas externas, normalmente concebidas como inertes desde un punto de vista moral, pueden considerarse lo que aquí se denominarán mediadores morales. Por lo tanto, no todas las herramientas morales están en el interior de nuestra cabeza, sino que muchas están distribuidas en objetos y estructuras externas que funcionan como dispositivos éticos. Con el objeto de investigar con detalle este conflicto ético entre los seres humanos y las cosas, consideraremos el papel que desempeñan los objetos, las estructuras y los artefactos tecnológicos mostrándolos como delegados y mediadores morales.

In this paper we seek an inferential and cognitive model explaining some characteristics of abduction to composite hypotheses. In the first section, we introduce the matter of composite hypotheses, stressing how it is coherent with the intuitive and philosophical contention that a single event can be caused not only by several causes acting together, but also by several kinds of causation. In the second section, we argue that gossip could serve as an interesting model to study the generation of composite hypotheses at a larger scale: several characteristics of gossip make it extremely prone to produce composite hypotheses considering different levels of causation. In the third and final section, we try to illustrate some specificities of abduction to composite hypotheses for individual agents basing on the analysis of collective agents.

What I call semiotic brains are brains that make up a series of signs and that are engaged in making or manifesting or reacting to a series of signs: through this semiotic activity they are at the same time engaged in “being minds” and so in thinking intelligently. An important effect of this semiotic activity of brains is a continuous process of disembodiment of mind that exhibits a new cognitive perspective on the mechanisms underling the semiotic emergence of meaning processes. Indeed at the roots of sophisticated thinking abilities there is a process of disembodiment of mind that presents a new cognitive perspective on the role of external models, representations, and various semiotic materials. Taking advantage of Turing’s comparison between “unorganized” brains and “logical” and “practical” machines” this paper illustrates the centrality to cognition of the disembodiment of mind from the point of view of the interplay between internal and external representations, both mimetic and creative. The last part of the paper describes the concept of mimetic mind I have introduced to shed new cognitive and philosophical light on the role of computational modeling and on the decline of the so-called Cartesian computationalism.

This paper aims at presenting a concise treatment of some key themes of my recent book Morality in a technological world. Knowledge as duty (Cambridge: Cambridge: Cambridge University Press, 2007). In recent times, non-human beings, objects, and structures – for example computational tools and devices - haveacquired new moral worth and intrinsic values. Kantian tradition in ethics teaches that human beings do not have to be treated solely as “means”, or as “things”, that is in a merely instrumental way, but also have to be treated as “ends”'. I contend that human beings can be treated as “things” in the sense that they have to be “respected” as things are sometimes. To the aim of reconfiguring human dignity in our technological world I introduce the concept of moral mediator.

The status of abduction is still controversial. When dealing with abductive reasoning misinterpretations and equivocations are common. What did Peirce mean when he considered abduction both a kind of inference and a kind of instinct or when he considered perception a kind of abduction? Does abduction involve only the generation of hypotheses or their evaluation too? Are the criteria for the best explanation in abductive reasoning epistemic, or pragmatic, or both? Does abduction preserve ignorance or extend truth or both? To study some of these conundrums and to better understand the concept of visual abduction, I think that an interdisciplinary effort is needed, at the same time fecundated by a wide philosophical analysis. To this aim I will take advantage of some reflections upon Peirce’s philosophy of abduction that I consider central to highlight the complexity of the concept, too often seen in the partial perspective of limited formal and computational models. I will ponder over some seminal Peircean philosophical considerations concerning the entanglement of abduction, perception, and inference, which I consider are still important to current cognitive research. Peircean analysis helps us to better grasp how model-based, sentential, manipulative, and eco-cognitive aspects of abduction—I have introduced in my book Abductive Cognition —have to be seen as intertwined, and indispensable for building an acceptable integrated model of visual abduction. Even if speculative, Peircean philosophical results on visual abduction certainly anticipate various tenets of recent cognitive research