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Dinesh

Dinesh club

Posted: 02 Aug 2013

Taken: 20 Sep 2009

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Excerpt •
Not by Genes alone •
Authors •
Peter J. Richerson •
& •
Robert Boyd •
Second excerpt •
The Invention of Science •
Author •
David Wootton •

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Eyes

Eyes
The curve of your eyes circles my heart
A round of dance and sweetness
And if I no longer know all that I have experienced
It is because your eyes have not always seen me.

Paul Eluard.
Comments
 Dinesh
Dinesh club
The existence of organs of extreme perfection like eyes was the main evidence of the existence of a supernatural Power that was manifestly required to design them, or so the argument went. The crudities and approximations rife in the actual design of organisms are much harder for Natural Theology. Vertebrate eyes have their nerve net lying on top of the photosensitive rods and cones, reducing their light sensitivity that requiring a blind spot where the nerves gather and dive through the retina to form the optic nerve. Octopus eyes, otherwise quiet similar in “design,” are much more sensibly enervated from behind. These differences make sense in terms of the development of these independently evolved camera eyes. The functionally backwards design of vertebrate eyes is only modestly maladaptive, but its transparent clunkiness betrays a history of evolution by the blind, stepwise improvement by natural selection rather than the hand of the Designer. ~ Page 151
5 years ago. Edited 4 years ago.
 Dinesh
Dinesh club
Intromission Theory

. . . .the ‘Optics’ of the first great experimental scientist, Ibn al-Haytham (965 - c1040), had been translated into Latin by 1230 (at which point Ibn al-Haytham acquired his Western name of Alhazen). It was soon widely available in manuscript and appeared in print in 1572. The puzzle is why Ibn al-Yaytham’s example was not followed more extensively, for it would be difficult to overestimate the significance of his achievement. Using a rigorous experimental method, he refuted the standard extromission theory of sight (that sight made possible by rays that go out from the eye) and defended the intromission theory (that sight is made possible by rays that enter the eye from the object); he produced the first full statement of the law of reflection, and also studied refraction; the designed the first true camera obscura; he made enormous advances toward an understanding of physiology of the eye (although he failed to grasp that an upside-down image is projected through the lens on the retina and at the back of the eye); and he laid the intellectual foundations of the science to artificial perspective. Medieval optics was heavily dependent upon his contribution and he was unquestionably the best example of an experimental scientist before Gilbert. ~ Page 319
3 years ago.

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