Quantum mechanics is often said to implicate some form of holism.
Quantum mechanics seems to portray nature as nonseparable. Roughly speaking, this means that quantum mechanics seems to allow two entities to be in separate places, while being in states that cannot be fully specified without reference to each other.
Quantum holism: nonseparability as common ground
by Jenann Ismael and Jonathan Schaffer
https://www.jonathanschaffer.org/quantumholism.pdf
Quantum mechanics seems to portray nature as nonseparable, in the sense that it allows spatiotemporally separated entities to have states that cannot be fully specified without reference to each other. This is often said to implicate some form of “holism.” We aim to clarify what this means, and why this seems plausible. Our core idea is that the best explanation for nonseparability is a “common ground” explanation (modeled after common cause explanations), which casts nonseparable entities in a holistic light, as scattered reflections of a more unified underlying reality.
3.1.1 Entanglement
The quantum formalism includes rules for assigning quantum states not just to simple systems but also to complex systems such as a pair of particles, an object system and a measuring apparatus, or an observer and her physical environment. These quan- tum states are what then get fed into the dynamics (Schrödinger’s Equation, or some descendant), and what then get used to derive probabilities of observables (Born’s Rule). The quantum state-spaces for complex systems allow for entangled states, which are states for the whole that cannot be reduced to states for the multiple com- ponents. The components of a system in an entangled state behave in ways that are individually unpredictable, but jointly constrained so that it is possible to forecast with certainty how one component will behave, given information about the measurements carried out on the other(s).