The concept of indistinguishable particles in quantum theory is fundamental to questions of ontology. All ordinary matter is made of electrons, protons, neutrons, and photons and they are all indistinguishable particles. Yet the concept itself has proved elusive, in part because of the interpretational difficulties that afflict quantum theory quite generally, and in part because the concept was so central to the discovery of the quantum itself, by Planck in 1900; it came encumbered with revolution.

I offer a deflationary reading of the concept ‘indistinguishable’ that is identical to Gibbs' concept ‘generic phase’, save that it is defined for state spaces with only finitely-many states of bounded volume and energy (finitely-many orthogonal states, in quantum mechanics). That, and that alone, makes for the difference between the quantum and Gibbsean concepts of indistinguishability.

This claim is heretical on several counts, but here we consider only the content of the claim itself, and its bearing on the early history of quantum theory rather than in relation to contemporary debates about particle indistinguishability and permutation symmetry. It powerfully illuminates that history.

量子理论中不可区分粒子的概念是本体论问题的基础。所有普通物质都是由电子，质子，中子和光子组成的，它们都是无法区分的粒子。然而，这个概念本身却难以捉摸，部分是由于普遍困扰量子理论的解释难题，部分原因是该概念对于1900年普朗克发现量子本身如此重要。它充满了革命。

我对“不可区分的”概念进行了通缩式的解读，与Gibbs的“一般阶段”相同，只是它定义为仅具有有限体积和能量的有限状态（有限的许多正交状态）的状态空间。量子力学）。仅此一点，就使量子和吉布森的不可区分性概念有所不同。

此主张在几个方面都是异端，但在这里我们仅考虑其本身的内容，以及它与量子理论的早期历史有关，而不是与有关粒子不可区分性和置换对称性的当代争论有关。它有力地阐明了这一历史。