The Extended Evolutionary Synthesis (EES) challenges the Modern Synthesis by rejecting a predominantly unidirectional causal model - characterised within the EES as natural selection acting on passive populations - and by emphasising organism-centred constructive processes. Despite significant support from philosophers and biologists, the EES remains a coalition of perspectives rather than a unified programme. Proponents have responded by appealing to British organicism, and to C. H. Waddington in particular, as a promising theoretical resource. Yet the payoff has remained unclear because organicism is typically treated as a monolithic and vaguely holistic worldview, and Waddington's concepts are often invoked piecemeal: scholars borrow his vocabulary without engaging with the deeper philosophical commitments that made those concepts coherent. This project reconstructs a fully Waddingtonian framework and offers a pluralistic, multi-timescale account of biological organisation. This account has the potential to better integrate the dynamics of development and evolution.

The project starts by offering the first fine-grained, comprehensive study of British organicist philosophy as it developed around the Cambridge Theoretical Biology Club and related networks. Rather than defining organicism merely in opposition to mechanism and vitalism, I reconstruct it around competing conceptions of biological organisation, showing how three distinct strands coexisted, interacted, and shaped one another over decades: (1) J. S. Haldane's idealistic organicism, which treats biological organisation as axiomatic; (2) Needham and Woodger's organising-relations organicism, which offers a realist account of biological organisation; and (3) Waddington's epigenetic organicism, which treats organised systems as temporally extended entities compatible with a pragmatic and pluralistic outlook. This reconstruction yields a less sanitised representation of Waddington: his influential biological ideas are best understood as components of a deeper philosophy of science, developed in active conversation with neo- Darwinism, fellow organicists, and A. N. Whitehead's process philosophy.

The project then extracts the contemporary payoff of this reconstruction. I show that many development-centred discussions operate largely within a Needham-Woodger-style framework, which has become increasingly compatible with New Mechanist approaches that study living systems as modular, dissociable, and hierarchically organised collections of entities whose organised activities and interactions give rise to phenomena. The EES, I argue, has the potential to become a fully Waddingtonian framework.

Drawing on Waddington's underdeveloped multi-timescale thinking, I develop two concepts as the theoretical core of this framework. Temporal alignment addresses how processes operating at different biological tempos are operationally coordinated in multi-scale research practice. I will explore the role of this practice in clarifying a pluralistic conception of biological organisation. Temporal entrainment proposes a criterion for causal selection: when explanatory frameworks span multiple timescales, the processes that entrain others are potential candidates to be treated as causally primary. Together, these concepts offer evo-devo and developmental biology a principled basis for addressing a problem that currently lacks one: how to conceptualise biological organisation in a pragmatic and pluralistic way, and how to select causally salient processes when explanatory frameworks integrate phenomena operating at radically different tempos.