# Scrutinizing microbiome determinism: why deterministic hypotheses about the microbiome are conceptually ungrounded

## TL;DR

This paper argues that deterministic claims about how host genetics or microbiome genetics determine traits are not supported by current scientific understanding.

## Contribution

The paper introduces and critiques two types of microbiome determinism using a novel philosophical framework.

## Key findings

- Host-microbiome determinism is prevalent but lacks conceptual grounding.
- Microbiome-phenotype determinism is similarly unsupported by current knowledge.
- The stability of traits framework challenges deterministic hypotheses in microbiome research.

## Abstract

This paper addresses the topic of determinism in contemporary microbiome research. I distinguish two types of deterministic claims about the microbiome, and I show evidence that both types of claims are present in the contemporary literature. First, the idea that the host genetics determines the composition of the microbiome which I call “host-microbiome determinism”. Second, the idea that the genetics of the holobiont (the individual unit composed by a host plus its microbiome) determines the expression of certain phenotypic traits, which I call “microbiome-phenotype determinism”. Drawing on the stability of traits conception of individuality (Suárez in Hist Philos Life Sci 42:11, 2020) I argue that none of these deterministic hypotheses is grounded on our current knowledge of how the holobiont is transgenerationally assembled, nor how it expresses its phenotypic traits.