What is the main idea behind the fixity of species?

The concept of the fixity of species is primarily associated with the idea that once a species is created, it does not change over time. This belief posits that species remain constant and unaltered, which contrasts significantly with later evolutionary theories that emphasize adaptation and change.

Historically, the fixity of species aligns with the viewpoints held by early naturalists and philosophers who viewed species as fixed entities designed by a creator, suggesting that any variations observed within a species were minor and did not reflect fundamental changes. The acceptance of fixity illustrates a pre-evolutionary understanding of biology and was a foundational element in discussions of species classification and characteristics prior to Darwinian evolution, which introduced the idea of species transforming and adapting over time in response to environmental pressures.

In this context, the other options reflect ideas about change, adaptation, and categorization that emerged later in biological thought.