Cleland C.E. The Quest for a Universal Theory of Life: Searching for Life As We Don’t Know It

Cambridge: Cambridge University Press, 2019. — 262 p.Integrating both scientific and philosophical perspectives, this book provides an informed analysis of the challenges of formulating a universal theory of life. Among the issues discussed are crucial differences between definitions and scientific theories and, in the context of examples from the history of science, how successful general theories develop. The central problem discussed is two-fold: first, our understanding of life is still tacitly wedded to an antiquated Aristotelian framework for biology; and second, there are compelling reasons for considering that familiar Earth life, which descends from a last universal common ancestor, is unrepresentative. What is needed are examples of life as we don't know it. Potential sources are evaluated, including artificial life, extraterrestrial life, and a shadow biosphere right here on Earth, and a novel strategy for searching for unfamiliar life in the absence of a definition or general theory is developed. The book is a valuable resource for graduate students and researchers studying the nature, origins, and extent of life in the universe.OverviewAristotle on the Nature of Life: Nutrition Versus Reproduction
Classical Mechanism about Life: From Optimism to Quiet Desperation
Darwin to the Rescue?
Here We Go Again: Aristotelian Roots of Contemporary Accounts of the Nature and Origin(s) of Life
Metabolism-Based Versus Evolution-Based Definitions of the Nature of Life
Metabolism-First Versus Genes-First Theories of the Origin(s) of Life
Concluding ThoughtsOverviewThermodynamic Definitions
Metabolic Definitions
Evolutionary Definitions
Defining Life as Self-Organized Complexity
Logical Character of Definition
Limits of Definition
Diagnosing the Problem: A Defective Theory of Meaning and Reference
Why Natural Kinds Cannot Be “Defined”
Is life an Exception to the Rule?
Concluding ThoughtsOverviewThe Syntactic Conception of Scientific Theories
The Semantic Conception of Scientific Theories
Scientific Theories and Definitions
Scientific Theories Do Not “Define” Natural Kinds
Nonstandard Definitions Do Not “Define” Scientific Theories
Concluding ThoughtsOverviewHow Scientifically Fruitful Ontologies Develop: Content Matters
The Goldilocks Level of Abstraction
The Threat Posed by Premature Commitment to Ontologies
The Monist (Versus Pluralist) Stance
Concluding ThoughtsOverviewThe Magnitude of the N = Problem of Biology
Microbes: The Most Representative and Least Well Understood Form of Earth Life
Planet of the Microbes
A Brief History of Misunderstandings and Surprises
The Problem of Contingencies and the Origin(s) of Life
A Plague of Contingencies (on Both the SM World and the RNA World)
The Origin Versus Nature Problem
Concluding ThoughtsOverviewEvolution Viewed Through the Lens of the Microbial World
The Concept of a Biological Species and the Tree of Life
Is Lamarck Hiding in the Shadows?
The Living Individual Viewed Through the Lens of the Microbial World
Is the Host–Microbiome Complex (Holobiont) a Living Thing?
Biofilms: Aggregates of Cells or Living Individuals?
Could Rock-Powered Ecosystems Be Living Things?
Concluding Thoughts
Soft ALife: Digital Organisms?
Hard ALife: Living Robots?
Synthetic Biology: Creating Novel Life in the Laboratory?
Concluding Thoughts
A Case Study: The Viking Missions to Mars
The Role of Anomalies in Scientific Discovery
Searching for Anomalies Using Tentative (Versus Defining) Criteria
Concluding ThoughtsOverviewHow Scientifically Plausible Is a Shadow Biosphere?
Did Life Originate Only Once on Earth?
Could the Present-Day Earth Be Host to a Shadow Biosphere?
Limitations to Microscopy
Limitations to Cultivation
Limitations to Metagenomic Methods
Potentially Biological Anomalies: Have We Already Encountered Them?
Concluding Thoughts