1,721,027 research outputs found
PROPOSITIONAL REASONING BY MODEL
No full textTwo theories of propositional deductive reasoning are considered: Johnson-Laird's mental models and Braine's mental logic. The model theory is said to account for practically all of the known phenomena of deductive propositional reasoning, offer a general theory of conditionals, account for the most important aspects of Braine's theory, and predict new phenomena that rule theories cannot explain. I argue that (a) the model theory is flawed in a way that is difficult to overcome, (b) conditionals are seriously misrepresented, (c) the algorithms proposed to implement it either allow invalid inferences or are psychologically useless, (d) Braine's theory accounts for all of the new phenomena worth considering, and (e) the model theory can predict Braine's results only at the cost of self-refutation. I conclude that the mental model theory of propositional reasoning offers no reason to reject the program of mental logic
The role of social capital in enhancing factor productivity: does its erosion depress per-capita GDP?
No full textWe aim at reconciling Putnam's claim that social capital has declined in the U.S. in the last decades with the satisfactory growth performance of the U.S. economy over the same period. This puzzle originates from the fact that - according to most literature - social capital enhances factor productivity (mainly by reducing defiant and opportunistic behavior). We model the hypotheses that the expansion of market activities weakens social capital formation, and that society reacts to the decline in social capital by spending more to protect property and enforce contracts. We show that this process may lead to a higher GDP level. © 2007 Elsevier Inc. All rights reserved
Endogenous growth and negative externalities
No full textWe augment an AK model by treating the units of time devoted to work as a choice variable and by introducing an environmental resource entering the households' utility function. In general, the resulting model does not generate endogenous growth in the absence of negative externalities: perpetual growth can be generated only when the resource deteriorates because of consumer activities. In this case, the households keep their labor supply and saving rates relatively high in spite of their increasing private wealth in order to consume more private goods as substitutes for the declining quality of the environment
How can transportation policies affect growth? A theoretical analysis of the long-term effects of alternative mobility systems
No full textWe present an example of how public policies affect the evolution of the economy by influencing consumption habits, life styles and work attitudes. In particular, we show that governments can boost long-run growth by moving public investment away from collective transportation systems and towards infrastructures necessary for using private vehicles. Indeed, by augmenting the relative convenience of using private mobility systems, which are those more costly for the households, the government induces them to increase their labour supply so as to afford larger expenditures in transportation. This has long-term welfare implications depending also on the negative externalities associated with transport. (C) 2013 Elsevier B.V. All rights reserved
Undesirable growth in a model with capital accumulation and environmental assets
No full textThe expansion of private production erodes the quality of commonly owned assets, thereby forcing individuals to rely increasingly on private goods to satisfy their needs. In the face of this deterioration, households increase their work effort and accumulate more capital in order to buy more consumer goods both in the present and in the future. By so doing, each household contributes to an increase in production and thus has a detrimental-though negligible-impact on commonly owned assets. Hence, the economy converges to a long-run equilibrium level of production that is higher than the level associated with the Pareto-efficient path
The inefficiency of patents when R&D projects are imperfectly correlated and imitation takes time
No full textIn a realistic framework where the potential innovators' research lines are imperfectly correlated and imitation takes some time, this paper studies an industry regulated by an authority that can subsidize the firms' R&D expenditures. By comparing the market equilibrium emerging when there is patent protection with the market equilibrium emerging without patents, the paper finds that social welfare is higher in the absence of patents. This result is driven by the fact that, without patents, more than one successful inventor may implement its discovery and enter the market, thus reducing the deadweight loss due to imperfect competition
Sulla possibile indeterminatezza della dinamica dell'aliquota di equilibrio di un sistema pensionistico
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