Editing Ibn al-Haytham (section)

== Other works ==

=== ''Influence of Melodies on the Souls of Animals'' ===

Alhazen also wrote a ''Treatise on the Influence of Melodies on the Souls of Animals'', although no copies have survived. It appears to have been concerned with the question of whether animals could react to music, for example whether a camel would increase or decrease its pace.

=== Engineering ===

In [[Inventions in the Islamic world|engineering]], one account of his career as a [[civil engineer]] has him summoned to Egypt by the Fatimid [[Caliph]], [[Al-Hakim bi-Amr Allah]], to regulate the [[flooding]] of the [[Nile]] River. He carried out a detailed scientific study of the annual [[inundation]] of the Nile River, and he drew plans for building a [[dam]], at the site of the modern-day [[Aswan Dam]]. His field work, however, later made him aware of the impracticality of this scheme, and he soon [[feigned madness]] so he could avoid punishment from the Caliph.<ref>{{harvnb|Plott|2000}}, Pt. II, p. 459.</ref>

=== Philosophy ===

In his ''Treatise on Place'', Alhazen disagreed with [[Aristotle]]'s view that nature abhors a [[Vacuum|void]], and he used [[geometry]] in an attempt to demonstrate that place (''al-makan'') is the imagined three-dimensional void between the inner surfaces of a containing body.<ref name="{{harvnb|el-bizri|2007}}.">{{harvnb|El-Bizri|2007}}.</ref> [[Abd al-Latif al-Baghdadi (medieval writer)|Abd-el-latif]], a supporter of Aristotle's philosophical view of place, later criticized the work in ''Fi al-Radd 'ala Ibn al-Haytham fi al-makan'' (''A refutation of Ibn al-Haytham's place'') for its geometrization of place.<ref name="{{harvnb|el-bizri|2007}}." />

Alhazen also discussed [[Depth perception|space perception]] and its [[Epistemology|epistemological]] implications in his ''[[Book of Optics]]''. In "tying the visual perception of space to prior bodily experience, Alhazen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for
correlation, sight can tell us next to nothing about such things."<ref>{{harvnb|Smith|2005|pp=219–240}}.</ref>

=== Theology ===
Alhazen was a Muslim and most sources report that he was a Sunni and a follower of the [[Ash'ari]] school.<ref name="ishaq">Ishaq, Usep Mohamad, and Wan Mohd Nor Wan Daud. "Tinjauan biografi-bibliografi Ibn al-haytham." Historia : Jurnal Program Studi Pendidikan Sejarah 5.2 (2017): 107–124.</ref><ref name="george">Kaminski, Joseph J. "The Trajectory of the Development of Islamic Thought{{snd}}A Comparison Between Two Earlier and Two Later Scholars." ''The Contemporary Islamic Governed State.'' Palgrave Macmillan, Cham, 2017. 31–70. "For example, Ibn al-Haytham and Abū Rayhān al-Bīrūnī were among the most important medieval scholars who used the scientific method in their approach to natural science, and they were both Ash'arites"</ref><ref name="Sardar 1998">{{harvnb|Sardar|1998}}</ref><ref name="Bettany 1995 251">{{harvnb|Bettany|1995|p=251}}</ref> [[Ziauddin Sardar]] says that some of the greatest [[Science in medieval Islam|Muslim scientists]], such as Ibn al-Haytham and [[Abū Rayhān al-Bīrūnī]], who were pioneers of the [[scientific method]], were themselves followers of the Ashʿari school of Islamic theology.<ref name="Sardar 1998" /> Like other Ashʿarites who believed that faith or ''taqlid'' should apply only to Islam and not to any ancient [[Hellenistic civilization|Hellenistic]] authorities,<ref>Anwar, Sabieh (October 2008), "Is Ghazālī really the Halagu of Science in Islam?", ''[[Al-Mawrid|Monthly Renaissance]]'', '''18''' (10), retrieved 14 October 2008</ref> Ibn al-Haytham's view that ''taqlid'' should apply only to [[prophets of Islam]] and not to any other authorities formed the basis for much of his [[scientific skepticism]] and criticism against [[Ptolemy]] and other ancient authorities in his ''Doubts Concerning Ptolemy'' and ''[[Book of Optics]]''.<ref>Rashed, Roshdi (2007), "The Celestial Kinematics of Ibn al-Haytham", ''Arabic Sciences and Philosophy'', [[Cambridge University Press]], '''17''' (1): 7–55 [11], {{doi|10.1017/S0957423907000355}}</ref>

Alhazen wrote a work on Islamic theology in which he discussed prophethood and developed a system of philosophical criteria to discern its false claimants in his time.<ref>{{harvnb|Plott|2000}}, Pt. II, p. 464</ref>
He also wrote a treatise entitled ''Finding the Direction of Qibla by Calculation'' in which he discussed finding the [[Qibla]], where prayers ([[salat]]) are directed towards, mathematically.<ref>{{harvnb|Topdemir|2007|pp=8–9}}.</ref>

There are occasional references to theology or religious sentiment in his technical works, e.g.
in  ''Doubts Concerning Ptolemy'':
{{blockquote|Truth is sought for its own sake ... Finding the truth is difficult, and the road to it is rough. For the truths are plunged in obscurity. ... God, however, has not preserved the scientist from error and has not safeguarded science from shortcomings and faults. If this had been the case, scientists would not have disagreed upon any point of science...<ref name=Sambursky1974>Translated by S. Pines, as quoted in {{harvnb|Sambursky|1974|p=139}}.</ref>}}
In ''The Winding Motion'':
{{blockquote|From the statements made by the noble Shaykh, it is clear that he believes in Ptolemy's words in everything he says, without relying on a demonstration or calling on a proof, but by pure imitation (''taqlid''); that is how experts in the prophetic tradition have faith in Prophets, may the blessing of God be upon them. But it is not the way that mathematicians have faith in specialists in the demonstrative sciences.<ref>{{harvnb|Rashed|2007|p=11}}.</ref>}}

Regarding the relation of objective truth and God:
{{blockquote|I constantly sought knowledge and truth, and it became my belief that for gaining access to the effulgence and closeness to God, there is no better way than that of searching for truth and knowledge.<ref>{{harvnb|Plott|2000}}, Pt. II, p. 465</ref>}}