Editing George Berkeley (section)

===New theory of vision===
In his ''Essay Towards a New Theory of Vision'', Berkeley frequently criticised the views of the Optic Writers, a title that seems to include [[William Molyneux|Molyneux]], Wallis, [[Nicolas Malebranche|Malebranche]] and [[René Descartes|Descartes]].<ref>Schwartz, R, 1994. Vision: Variations on some Berkeleian themes. Oxford: Blackwell, p. 54.</ref> In sections 1–51, Berkeley argued against the classical scholars of optics by holding that: ''spatial depth, as the distance that separates the perceiver from the perceived object is itself invisible''. That is, we do not see space directly or deduce its form logically using the laws of optics. Space for Berkeley is no more than a contingent expectation that visual and tactile sensations will follow one another in regular sequences that we come to expect through habit.

Berkeley goes on to argue that visual cues, such as the perceived extension or 'confusion' of an object, can only be used to indirectly judge distance, because the viewer learns to associate visual cues with tactile sensations. Berkeley gives the following analogy regarding indirect distance perception: one perceives distance indirectly just as one perceives a person's embarrassment indirectly. When looking at an embarrassed person, we infer indirectly that the person is embarrassed by observing the red colour on the person's face. We know through experience that a red face tends to signal embarrassment, as we've learned to associate the two.

The question concerning the visibility of space was central to the Renaissance [[Perspective (graphical)|perspective]] tradition and its reliance on classical optics in the development of pictorial representations of spatial depth. This matter has been debated by scholars since the 11th-century Arab polymath and mathematician [[Alhazen]] (Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham) affirmed in experimental contexts the visibility of space. This issue, which was raised in Berkeley's theory of vision, was treated at length in the ''Phenomenology of Perception'' of [[Maurice Merleau-Ponty]], in the context of confirming the visual perception of spatial depth (''la profondeur''), and by way of refuting Berkeley's thesis.<ref>For recent studies on this topic refer to: [[Nader El-Bizri]], 'La perception de la profondeur: [[Alhazen]], Berkeley et Merleau-Ponty', ''Oriens-Occidens: Cahiers du centre d'histoire des sciences et des philosophies arabes et médiévales'', [[Centre National de la Recherche Scientifique]] Vol. 5 (2004), pp. 171–84.  See also: [[Nader El-Bizri]], "A Philosophical Perspective on Alhazen's Optics", ''Arabic Sciences and Philosophy'', Vol. 15 (2005), pp. 189–218 ([[Cambridge University Press]] journal), {{doi|10.1017/S0957423905000172}}.</ref>

Berkeley wrote about the perception of size in addition to that of distance. He is frequently misquoted as believing in size–distance invariance—a view held by the Optic Writers. This idea is that we scale the image size according to distance in a geometrical manner. The error may have become commonplace because the eminent historian and psychologist [[Edwin Boring|E. G. Boring]] perpetuated it.<ref>Boring E. G., 1942. Sensation and perception in the history of experimental psychology. New York: Appleton-Century-Crofts, pp.&nbsp;223, 298.</ref> In fact, Berkeley argued that the same cues that evoke distance also evoke size, and that we do not first see size and then calculate distance.<ref>Ross H. E., Plug, C., 1998. "The history of size constancy and size illusions." In Walsh, V. & Kulikowski, J. (Eds). ''Perceptual constancy: Why things look as they do''. Cambridge: Cambridge University Press, 499–528.</ref> It is worth quoting Berkeley's words on this issue (Section 53):
<blockquote>What inclines men to this mistake (beside the humour of making one see by geometry) is, that the same perceptions or ideas which suggest distance, do also suggest magnitude ... I say they do not first suggest distance, and then leave it to the judgement to use that as a medium, whereby to collect the magnitude; but they have as close and immediate a connexion with the magnitude as with the distance; and suggest magnitude as independently of distance, as they do distance independently of magnitude.</blockquote>

Berkeley claimed that his visual theories were "vindicated" by a 1728 report regarding the recovery of vision in a 13-year-old boy operated for congenital cataracts by surgeon William Cheselden. In 2021, the name of Cheselden's patient was published for the first time: Daniel Dolins.<ref name=":10">{{cite journal|last1=Leffler|first1=CT|last2=Schwartz|first2=SG|date=February 2021|title=The First Cataract Surgeons in the British Isles|url=https://www.researchgate.net/publication/350148285|journal=American Journal of Ophthalmology|volume=230|pages=75–122|doi=10.1016/j.ajo.2021.03.009|pmid=33744237|pmc=8446104}}</ref> Berkeley knew the Dolins family, had numerous social links to Cheselden, including the poet Alexander Pope, and Princess Caroline, to whom Cheselden's patient was presented.<ref name=":10" /> The report misspelt Cheselden's name, used language typical of Berkeley, and may even have been ghost-written by Berkeley.<ref name=":10" /> Unfortunately, Dolins was never able to see well enough to read, and there is no evidence that the surgery improved Dolins' vision at any point prior to his death at age 30.<ref name=":10" />