# Explanations for failures in designed and evolved systems

## TL;DR

This paper compares why machines and organisms fail, showing how biological systems differ from engineered ones in design and vulnerability.

## Contribution

It highlights fundamental differences in failure explanations between engineered and biological systems, challenging the machine metaphor for organisms.

## Key findings

- Global failure explanations like design deficiencies apply to both machines and organisms.
- Biological trade-offs prioritize gene transmission over health, unlike engineered trade-offs.
- The machine metaphor for bodies can lead to a misleading understanding of biological complexity.

## Abstract

Engineers have long studied the origins of design features that make machines prone to failure, but biologists have only recently begun investigating why organisms have traits that make them susceptible to disease. This article compares explanations for vulnerability to failure in machines with explanations for traits that make bodies vulnerable to disease. Some global explanations are relevant for both: design deficiencies, corrupted plans, assembly variations, incorrect operating environment, and trade-offs. These similarities suggest that a common framework for failure analysis could be valuable. However, a closer look at each of the 10 global categories reveals fundamental differences: machines are built to match an ideal blueprint, while species have no perfect genome or form. Design trade-offs in machines involve balancing multiple factors such as performance, robustness, and costs, while biological trade-offs maximize only gene transmission, often at the expense of health and lifespan. Detailed consideration of these and other differences reveals how the metaphor of body as a designed machine fosters tacit creationism that misrepresents the nature of organically complex systems.