Reasoning about Unreliable Actions

We analyse the philosopher Davidson's semantics of actions, using a strongly typed logic with contexts given by sets of partial equations between the outcomes of actions. This provides a perspicuous and elegant treatment of reasoning about action, analogous to Reiter's work on artificial intelligence. We define a sequent calculus for this logic, prove cut elimination, and give a semantics based on fibrations over partial cartesian categories: we give a structure theory for such fibrations. The existence of lax comma objects is necessary for the proof of cut elimination, and we give conditions on the domain fibration of a partial cartesian category for such comma objects to exist

DEGREES OF COMPETITION, THE RATE OF RETURN AND GROWTH FROM A CLASSICAL/SRAFFIAN PERSPECTIVE

The purpose of the paper is a clarification of the concept of competition from a classical/ Sraffian perspective; including an elucidation of how a classical/Sraffian approach might go about defining the degree of competition. This in turn allows for a sharper contrast between the Sraffian view of competition and mainstream views. The starting point for the analysis is the work of Clifton which interprets the classical/Sraffian view of competition as more general than that of orthodoxy: one which can encompass competition between production units in a given industry as something constrained by more dominant forms of competition such as that between production units across industries for shares of the corporate surplus. Following on from the work of both Clifton and Semmler, and starting from the assumption that multi-divisional corporation is the relevant "firm", and that the corporate target rate of return is the relevant rate of profit, the question arises as to what determines the latter. And this question has received very little attention outside the more traditional post-Keynesian literature on pricing. The paper explores what is probably the most serious attempt within this literature - in the work of Eichner - to explain the target rate, in terms the desired growth rate of the corporation. This proposition has some interesting implications for a Sraffian approach, not least because it allows a link running from the expected growth of the economy to the target rate and thus the rate of profit. This in turn requires a discussion of the consistency of such a link with the Sraffian critique of the Cambridge growth equation. As well, a link between the target rate of return and the desired corporate growth rate link also has implications for the mechanics by which sectoral profit rates converge and thus for the classical/Sraffian literature on cross-dual dynamics .

DEMAND-LED GROWTH IN A MULTI-COMMODITY MODEL WITH LEARNING: SOME PRELIMINARY RESULTS

The paper represents a preliminary attempt to shed light on the following question: in the context of demand-led growth, how does learning by agents about the economic system's structure and the determinants of long-run growth affect the long-run dynamics of the economy? Analysis is conducted in terms of an extension of the simplified two-sector model with autonomous demands in White (2008). The focus of the analysis is on the impact of learning about two mechanisms in particular: about how the growth of autonomous demand influences growth of the economy as a whole; and about how expectations about growth affect the dynamics of growth. The mechanics of learning are twofold: first, a simple gradient-descent rule, whereby key coefficients in the investment function relating producers expectations about growth to past growth in their own sector and in the economy are modified in a way which aims to minimize forecast errors; and, second, a more ambitious mechanism whereby producers attempt to uncover aspects of the true relation between past growth rates and expected growth rates. Analysis of the system's dynamics is primarily by means of computer simulation.

Demand-led growth with debt constraints

The paper explores the implications of different autonomous demands, with differing rates of growth, in a demand-led growth model where policy makers are concerned about the ratios of public sector debt to income and external debt to income. The actual growth rate is explained in terms of the growth rate of aggregate demand, with emphasis in the formation of expectations about growth in the latter; and the relative importance in this regard of realised aggregate demand growth and autonomous demand growth, the latter being governed by export demand and public sector expenditure. Debt constraints - specifically, the ratio of public sector debt to output and the ratio of external debt to output - become relevant in the determination of the growth rate of government expenditure. The paper explores the likely interactions between debt constraints, the growth rate of aggregate demand and autonomous demand by means of dynamic simulations.government expenditure; debt; Autonomous demand; growth