Hi Miguel - I gathered that the contents of the philosophical article you linked to revolve around an objection raised by the article’s author Brigitte Faulkenburg to what she perceives to be Alex Gelfert’s misapplication of Ian Hacking’s criterion for evaluating/ determining the existence of an entity, in this case as it pertains to the existence of quasi-particles. Hacking summed up his criterion for evaluating the existence/ reality of an entity as: "If you can spray them, they exist”; in other literature he’s quoted, in reference to the existence of electrons, “so far as I’m concerned, if you can spray them, then they are real.” This criterion for evaluating the reality/ existence of an entity is associated with what is known as “Entity Realism”, a philosophical position which only regards as real or existent those entities that can manipulate or be manipulated, i.e., “you can spray them.” If the entity in question cannot demonstrate measurable effects then, by Hacking’s criterion, it does not exist.
Wikipedia: … ‘electrons’, should be regarded as real if and only if they refer to phenomena that can be routinely used to create effects in domains that can be investigated independently. ‘Manipulative success’ thus becomes the criterion by which to judge the reality of (typically unobservable) scientific entities. As Ian Hacking, the main proponent of this formulation of entity realism, puts it (referring to an experiment he observed in a Stanford laboratory, where electrons and positrons were sprayed, one after the other, onto a superconducting metal sphere), “if you can spray them, then they are real.”
Entity realism - Wikipedia
According to Faulkenburg, Gelfert exhibited dubious reasoning when he pointed out in his paper that the mere ability of a quasi-particle to demonstrate “manipulative success”, the essential component for satisfying Hacking’s criterion, does not necessarily reveal any genuine existence of the entity, particularly when knowledge of the nature and substance of that entity lacks what he regards as “home truths”, or subjectively familiar non-theoretical knowledge:
Faulkenburg: Gelfert’s conclusion that quasi-particles are not genuine entities, and (given their manipulative success) thus counter Hacking’s reality criterion, is based on an ambiguity in his notion of “home truth” . . . [which] are based on traditional metaphysical ideas about independent substances."
Faulkenburg finds that Gelfert’s position as a philospher, as opposed to a physicist, caused him to overlook how knowledge of the nature of quasi-particles could be considered to be rooted in so-called “home truths”, when viewed from the perspective of a physicist:
Faulkenburg: One should carefully distinguish the physicist’s and the philosopher’s “home truths”. The physicist’s “home truths” consist in familiar background knowledge about measurement methods, physical quantities such as mass/energy, charge, spin, etc., and also (a century after the rise of quantum theory) basic knowledge about quantum mechanics . . . . In contradistinction to this background knowledge of quantum physics, however, the philosopher’s “home truths” about what genuine entities should be like are rooted in metaphysics.
Faulkenburg goes on to address objections raised about the genuineness of quasi-particles based on their status of existing as “collective effects” as opposed to existing as independent entities:
Faulkenburg: Given that they do not exist on their own but only as collective effects, they seem to be fake entities rather than physical particles.
She finds that objection misplaced, and concludes the genuine reality of quasi-particles, after equating the ontological nature of quasi-particles to other phenomena that could be classified as “collective effects” yet whose existence is acknowledged and undisputed:
Faulkenburg: Indeed, quasi-particles are as real as a share value at the stock exchange. The share value is also due to a collective effect (as the very term indicates), namely the collective behavior of all investors. The analogy may be extended. It is also possible to ‘spray’ the share value in Hacking’s sense, that is, to manipulate its quotation by purchase or sale for purposes of speculation. … But would we conclude that the share value does not exist, on the sole grounds that it is a collective effect?
Relevant to the discussions that took place in Drawing a line between feeling and fact, she distinguishes between the nature of quasi-particles, which she considered to genuinely exist, and between other types of entities which she does not consider as having genuine existence, such as the mythological creature Pegasus, which she says only exists “in the tales of ancient mythology” as opposed to what she calls the “real world.”
Faulkenburg: Obviously, share values as well as quasi-particles have another ontological status than, say, Pegasus. Pegasus does not exist in the real world but only in the tales of ancient mythology.
One of my central positions in that discussion, which was articulated in 11,000+ words and will be briefly summed up here for context, was that the fact that something exists somewhere and somehow, wherever that place is – whether in the brain, in books, on television, on mountains, on beaches, on Pluto, anywhere at all – then it exists, full stop. I drew attention to the obvious fact that only existent things exist (by definition), as well as to the obvious fact that non-existent things do not exist (by definition); and because the universe (aka everything there is) exists, then literally everything exists … which means there is literally nothing that does not exist. Whether that something which exists arises inside the mind or outside of the mind doesn’t negate the fact that it exists. Finally, that which exists in fact …
Richard (2000): … actual (existing in fact) …
Mailing List 'C' Respondent No. 3
Richard (2001): … the word ‘actual’ commonly means ‘existing in act or fact …
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Richard (1998): …‘actual’: truly existing.
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Richard (1998): … actual means: ‘already occurring; existing as factually true’.
Mailing List 'B' Respondent No. 14