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This Thesis engages with contemporary philosophical controversies about the nature of dispositional properties or powers and the relationship they have to their non-dispositional counterparts. The focus concerns fundamentality. In particular, I seek to answer the question, ‘What fundamental properties suffice to account for the manifest world?’ The answer I defend is that fundamental categorical properties need not be invoked in order to derive a viable explanation for the manifest world. My stance is a field-theoretic view which describes the world as a single system comprised of pure power, and involves the further contention that ‘pure power’ should not be interpreted as ‘purely dispositional’, if dispositionality means potentiality, possibility or otherwise unmanifested power or ability bestowed upon some bearer. The theoretical positions examined include David Armstrong’s Categoricalism, Sydney Shoemaker’s Causal Theory of Properties, Brian Ellis’s New Essentialism, Ullin Place’s Conceptualism, Charles Martin’s and John Heil’s Identity Theory of Properties and Rom Harré’s Theory of Causal Powers. The central concern of this Thesis is to examine reasons for holding a pure-power theory, and to defend such a stance. This involves two tasks. The first requires explaining what plays the substance role in a pure-power world. This Thesis argues that fundamental power, although not categorical, can be considered ontologically-robust and thus able to fulfil the substance role. A second task—answering the challenge put forward by Richard Swinburne and thereafter replicated in various neo-Swinburne arguments—concerns how the manifestly qualitative world can be explained starting from a pure-power base. The Light-like Network Account is put forward in an attempt to show how the manifest world can be derived from fundamental pure power.

[pt] O objetivo desse trabalho é desenvolver um essencialismo sem mundos possíveis. Alegamos que objetos ordinários são entidades complexas constituídas por entidades mais básicas como pedaços de matéria e propriedades instanciadas Os possíveis constituintes são determinados pela realidade, independentes da mente e linguagem humana, mas a constituição é convencional dependente do nosso esquema conceitual e as nossas práticas de nomeação. Consequentemente desenvolvemos uma teoria aristotélica de objetos ordinários como complexos de suas essências e da matéria que instancia essas essências. Em seguida aplicamos essa concepção de objetos para modificar a teoria da referência direta. Nessa teoria resultante, os significados de nomes próprios são as essências dos referentes desses nomes. O quadro da nossa investigação consiste numa teoria plantonista de propriedades segundo a qual as propriedades são partes integrais de uma realidade complexas sendo interconectadas com a parte concreta dessa realidade e na qual algumas propriedades podem participar em relações causais. De acordo com isso, apresentamos uma concepção atualista de modalidades na qual as modalidades ocorrem em virtude de relações de segunda ordem entre propriedades, no caso de modalidades de re em virtude de relações de segunda ordem entre essências de objetos e outras propriedades. / [en] The aim of this study is to develop an essentialist theory without possible worlds. We claim that ordinary objects are complex entities composed of entities that are more basic like pieces of matter and instantiated properties. The possible constituents are determined by reality and mind- and language-independent, the constitution, however, is conventional dependent on our conceptual scheme and our naming practices. In consequence, we develop an Aristotelian theory of ordinary objects as complexes of their essences and the matter which instantiates these essences. We apply this conception of objects in order to modify the direct reference theory. In the resulting theory, the meanings of proper names are the essences of the bearers of the names. The theoretical frame of our investigation consists in a Platonist theory of properties according to which properties are integral parts of a complex reality connected with its concrete partand in which some properties can participate in causal relations. In accordance with this view, we present an actualist conception of modalities in which modalities obtain in virtue of second order relations between properties, in case of de re modalities in virtue of second order relations between objects essences and other properties.

We demonstrate a remarkable property of metallic Fermi liquids: the transverse conductivity assumes a universal value in the quasi-static (ω → 0) limit for wavevectors q in the regime l −1 mfp q pF, where lmfp is the mean free path and pF is the Fermi momentum. This value is (e2/h)RFS/q in two dimensions (2D), where RFS measures the local radius of curvature of the Fermi surface (FS) in momentum space. Even more surprisingly, we find that U(1) spin liquids with a spinon FS have the same universal transverse conductivity. This means such spin liquids behave effectively as metals in this regime, even though they appear insulating in standard transport experiments. Moreover, we show that transverse current fluctuations result in a universal low-frequency magnetic noise that can be directly probed by a spin qubit, such as a nitrogen-vacancy (NV) center in diamond, placed at a distance z above of the 2D metal or spin liquid. Specifically the magnetic noise is given by CωPFS/z, where PFS is the perimeter of the FS in momentum space and C is a combination of fundamental constants of nature. Therefore these observables are controlled purely by the geometry of the FS and are independent of kinematic details of the quasi-particles, such as their effective mass and interactions. This behavior can be used as a new technique to measure the size of the FS of metals and as a smoking gun probe to pinpoint the presence of the elusive spinon FS in two-dimensional systems. We estimate that this universal regime is within reach of current NV center spectroscopic techniques for several spinon FS candidate materials.