Theory of Collective Action

Theory predicts that when people pursue their selfish aims then it leads to suboptimal outcomes for society or to the group they belong to. The prisoner\u27s dilemma and the tragedy of the commons are classic examples. In her presidential lecture to the American Political Science Association Elinor Ostrom examined this fact and also noted that in practice people do not always follow the suboptimal strategy. What does she suggest? This document consists of slides I created giving an account of her paper. She had not won the Nobel when she gave this talk but it was conferred on her later

Logic, Co-ordination and the Envelope of our Beliefs

Each of us has a story which we can think of as a set of beliefs, hopefully consistent. We make our decisions in view of our beliefs which may be probabilistic, in the general case, but simple yes or no as in this paper. Our beliefs are our envelope just as the shell of a tortoise is its envelope. Decision theory - or single agent game theory tells us when to make the best choice in a game of us against nature. But nature has no desire to further or frustrate our efforts. Nature is mysterious but not malign. Things change when there are other agents involved. Then the best thing for us to do will depend on what they do. And they will think the same. And we predict their actions in terms of what we think their beliefs are. But how do we coordinate with others whose beliefs are different? This paper addresses the issue of working together despite different beliefs

D-structures and their semantics

Many logicians are familiar with the game theoretic approach to semantics, due to Jaakko Hintikka. This paper by me contains class notes of a logic course at Boston University in fall 1972. It has similar game theoretic ideas, developed quite independently, but influenced by the work of A. Ehrenfeucht. It applies to a larger class of logics, including classical logic, intuitionistic logic and the *-semantics of Ehrenfeucht. The treatment is via D-structures which are finite approximations of infinite structures. For various reasons I did not publish this paper then, but some abstracts, both by myself as well as joint abstracts with Dick De Jongh, Nick Goodman and John Mayberry WERE published in 1972 in the notices of the AMS as well as the Journal of Symbolic Logic. The paper itself finally appeared in the volume to celebrate the 50th birthday of Johan van Benthem

How Groupy is a Group?

Various Cooperating Groups Why and how do they cooperate Bees Chinese troops BLM demonstrators The reasons are different in the three cases. 1) Bees cooperate because they are all sisters who have thesame DNA. From a purely evolutionary point of view the survival of one is the survival of all. 2) Chinese troops cooperate because they are obeying a single commander. 3) Black lives people cooperate because they have a single goal, and they have communicated to be together at one time and place. The purpose of this work is to provide a definition of the amount of groupiness, revealed by coordination in their choices

On Kripke\u27s puzzle about time and thought

We discuss a variant of a puzzle introduced by Saul Kripke

On Public Language and Private Language

It is discussed how a discussion of private experiences and qualia can arise in personal life. The examples used are an accident with a truck and a possible operation by researchers at CUNY

Logic and Rationality

Logic aims at truth, or more accurately, at deriving some truths from other truths. But why are we interested in truth in the first place? Surely one reason is that relying on truth makes it easier to make better choices. One could think of Game theory as a tool which bridges the gap between logic and rationality. Decision theory - or single agent game theory tells us when to make the best choice in a game of us against nature. But nature has no desire to further or frustrate our efforts. Nature is mysterious but not malign. Things change when there are other agents involved. Then the best thing for us to do will depend on what they do. And they will think the same. Issues like common knowledge and rationalizability will then arise

Algorithmic Rationality

The notion of rationality is much discussed by both Economists and Philosophers. Perhaps you are rational if you accept certain axioms of rationality. If you prefer A to B and B to C then you must prefer A to C. Or you can define rationality in terms of the net results of your behavior. We examine a notion of algorithmic rationality. Even animals upwards from the humble tick carry out algorithms. Are they rational? And can we use this theory to define the IQ of animals

Formalizing the Umwelt

In the early part of the XXth century, Jacob from Uexkuell introduced the notion of the Umwelt which is the personal world which animals and humans live in. It is understood that each of us has our own Umwelt. This paper is an attempt to understand the notion of Umwelt using tools from logic and decision theory

Covid-19 and Knowledge Based Computation

The problem of dealing with Covid-19, until a vaccine is universally administered, is to decrease the rate of transmission while getting some social and economic activity going. Infection passes from one person A to another person B when A is infected and B is susceptible. That is to say that B is not infected and not yet immune. Social activity also takes place when one person interacts with another. Perhaps A is a taxpayer and B is a tax consultant. Then filing the tax return may take the form of the two of them meeting. Much can be done electronically without such a meeting, but if A is a person who needs a haircut and B is a barber then it seems that it is necessary for the two to meet in order that A gets his haircut