Classifying and characterizing active materials

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1 Scopus citations


This article examines the distinction between active matter and active materials, and it offers foundational remarks toward a system of classification for active materials. Active matter is typically identified as matter that exhibits two characteristic features: self-propelling parts, and coherent dynamical activity among the parts. These features are exhibited across a wide range of organic and inorganic materials, and they are jointly sufficient for classifying matter as active. Recently, the term “active materials” has entered scientific use as a complement, supplement, and extension of “active matter.” At the same time, new work in the philosophy of science has considered the problem of how to classify the products of synthetic and laboratory processes, and the extent to which the aims of classifying natural kinds compare and contrasts with the aims of classifying these synthetic kinds. In this article, I apply those considerations to the problems of classifying and characterizing active materials. In doing so, I also argue for a conception of active materials’ coherent dynamical activity as multiscale, rather than emergent, and I discuss how the special non-equilibrium status of active materials factors in to classificatory concerns.

Original languageEnglish
Pages (from-to)2007-2026
Number of pages20
Issue number1-2
StatePublished - Dec 2021

Bibliographical note

Funding Information:
Many thanks to the organizers and sponsors of the 2017 and 2018 Georgetown Active Materials Project Summer Schools for turning my attention to this topic and supplying opportunities to pursue it, and to all of the other participants for the stimulating conversations that led to these collected thoughts. Thanks especially to Daniel Blair, Zvonimir Dogic, Daniel Needleman, and Cynthia Reichhardt for sharing their scientific expertise; to Bob Batterman, Bill Bechtel, Alisa Bokulich, Nick Brancazio, Sara Green, Robin Hendry, Jacob Neal, Beau Revlett, and Collin Rice for insightful discussions during the summer schools; to Melinda Fagan and Michela Massimi for additional discussion about synthetic kinds and feedback on drafts; to Patrick McGivern for organizing the Special Issue; and to two anonymous reviewers for very thoughtful and constructive comments. As ever, thanks to STARS.

Publisher Copyright:
© 2020, Springer Nature B.V.


  • Active materials
  • Classification
  • Multi-scale modeling
  • Natural kinds
  • Smart materials

ASJC Scopus subject areas

  • Philosophy
  • Social Sciences (all)


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