Rationality in Discovery - a study of Logic, Cognition, Computation and Neuropharmacology
Alexander van den Bosch

Abstract:
%Nr: DS-2001-01
%Author: Alexander P.M. van den Bosch
%Title: Rationality in Discovery A Study of Logic, Cognition, Computation and 
Neuropharmacology


Part I Introduction

The specific problem adressed in this thesis is: what is the rational use of 
theory and experiment in the process of scientific discovery, in theory and 
in the practice of drug research for Parkinson's disease? The thesis aims to 
answer the following specific questions: what is: 1) the structure of a 
theory?; 2) the process of scientific reasoning?; 3) the route between theory 
and experiment? In the first part I further discuss issues about rationality 
in science as introduction to part II, and I present an overview of my 
case-study of neuropharmacology, for which I interviewed researchers from the 
Groningen Pharmacy Department, as an introduction to part III.

Part II Discovery

In this part I discuss three theoretical models of scientific discovery 
according to studies in the fields of Logic, Cognition, and Computation. In 
those fields the structure of a theory is respectively explicated as: a set 
of sentences; a set of associated memory chunks; and as a computer program 
that can generate the observed data. Rationality in discovery is 
characterized by: finding axioms that imply observation sentences; heuristic 
search for a hypothesis, as part of problem solving, by applying memory 
chunks and production rules that represent skill; and finding the shortest 
program that generates the data, respectively. I further argue that reasoning 
in discovery includes logical fallacies, which are neccesary to introduce new 
hypotheses. I also argue that, while human subjects often make errors in 
hypothesis evaluation tasks from a logical perspective, these evaluations are 
rational given a probabilistic interpretation.

Part III Neuropharmacology

In this last part I discusses my case-study and a model of discovery in a 
practice of drug research for Parkinson's disease. I discuss the dopamine 
theory of Parkinson's disease and model its structure as a qualitative 
differential equation. Then I discuss the use and reasons for particular 
experiments to both test a drug and explore the function of the brain. I 
describe different kinds of problems in drug research leading to a discovery. 
Based on that description I distinguish three kinds of reasoning tasks in 
discovery, inference to: the best explanation, the best prediction and the 
best inter-vention. I further demonstrate how a part of reasoning in 
neuropharmacology can be computationally modeled as qualitative reasoning, 
and aided by a computer sup-ported discovery system