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Dublin born Thomas Kingsmill Abbott (26 March 1829 – 18 December 1913) is probably best known for his translations of Kant’s ethical works published in 1873 which remained the standard English texts into the 1940s (Duddy, 2004). He had a wide range of scholarly interests, being professor various of Moral Philosophy, Greek and Hebrew in Trinity College Dublin. However his greatest philosophical contribution was made in his early career, where he disputed the theory of vision outlined by (fellow Trinity man) George Berkeley.
The roots of Berkeley’s theory are in Locke. Just before he introduces (William) Molyneaux’s Problem, in his Essay on Human Understanding (IX, 8) Locke states that “When we set before our eyes a round globe of any uniform colour […] it is certain that the idea thereby imprinted on our mind is of a flat circle”. The roundness we think we see, says Locke, is the effect of experience, which differentiates what we see: “…only a plane variously coloured, as is evident in painting.” He does not, however, claim we cannot tell that the sphere is at a distance.
William Molyneaux does claim this, however, in his Dioptrica Nova (1692, 113):
Distance of itself is not to be perceived. For it is a line (or a length) presented to our eye with its end toward us which must therefore be only a point, and that is invisible.
Berkeley expands these ideas in A Essay towards a New Theory of Vision (1709/1732), referenced previously in relation to the Moon Illusion. Berkeley agrees with Molyneaux that distance cannot be seen (II):
Distance, of itself and immediately, cannot be seen. For distance being a line directed endwise to the eye it projects only one point in the fund of the eye, which point remains invariably the same, whether the distance be longer or shorter
Distance and three-dimensionality, Berkeley says, are only discoverable to us through touch. There are no ideas common to the senses, so we must link ideas from sight and ideas from touch through experience (127). “The Pictures Painted on the Bottom of the Eye, are not the Pictures of External Objects” (117) – the sight of an object cannot prepare us for the feel of it, and vice versa. Much like Fr Dougal, who need Fr Ted to teach him that these are small and those are far away, Berkeley thinks that we cannot tell by looking alone.
This theory, that we do not see objects as being in a three-dimensional space, became orthodoxy in the 18th and 19th centuries. It was espoused by Hume and argued for by Mill, with few dissenters. (See Smith, 2000, “Space and Sight”, sections I and II for a full account.) Abbott himself called it “a single discovery in mental science that is universally admitted” (p 1.)
Abbott points out that this contradicts the common-place view. When someone is asked why they think a cow is far away they will say, “I see it is”. Looking at a landscape (p. 20)
What countless objects we see, at distances no less various, not one in ten thousand of which we ever touch, still less think of measuring its distance; yet it is a fact that [they]…appear to be seen at a certain distance
We clearly don’t use touch to estimate these distances, and touch is especially unsuited to do so since nothing has any existence for touch “which is not actually in contact with the surface of the body” (p. 60). Touch cannot sense the distance between one felt surface and another. There is merely an interval of time between them.
Arguments that ideas of effort produce the concept of distance are rebutted by pointing out the relationship doesn’t hold: moving a pen requires labour, without the pen appearing far away. As for the possibility of learning to relate differences in appearance with distance Abbott points out that both humans and animals “would be ill-provided indeed if brightness and visible magnitude were the only means of perceiving distance” (p. 171). How is the creature to survive if (as for Fr Dougal) the process of seeing distance (of food or predators) requires a laborious learning process?
(c) Justin Hanes Magician (CC BY-NC-SA 2.0)
Abbott systematically showed that Berkeley’s theory of vision was wrong. However it did not demonstrate that Berkeley’s idealism was untrue. As Down-man William Graham (1839-1911) argued, sight and touch were in Berkeley’s theory modes of conscious experience and remained so whether it was sight or touch that perceived distance (Duddy, 2002). Abbott’s critique of Berkeley, however, still remains important.
Acknowledgement
Thanks to @modernphilosophy who linked me to Smith’s paper and who tweeted Berkeley’s thoughts on distance (see below). Also @tomstoneham who tweeted the Molyneaux quote (also see below).
References
Thomas Duddy, 2004, “Abbott, Thomas Kingmill” in Dictionary of Irish Philosophers.
Thomas Duddy, 2002, A History of Irish Thought pp. 276-7.
A. D. Smith, 2000, “Space and Sight” in Mind, Vol. 109, No. 435 (Jul., 2000), pp. 481-518 (on JSTOR)
Both the 1709 and the 1732 versions of An Essay towards a new Theory of Vision are available here
Thomas Kingsmill Abbott, 1864, Sight and Touch (on archive.org)
Berkeley's argument: "Distance, of itself and immediately, cannot be seen. For distance being a line directed endwise to the eye…" (1/2)
— Early Modern Tweets (@EarlyModPhil) December 16, 2014
it projects only one point in the fund of the eye, which point remains invariably the same, whether the distance be longer or shorter" (2/2)
— Early Modern Tweets (@EarlyModPhil) December 16, 2014
@EarlyModPhil Distance of itself is not to be perceived. For it is a line (or a length) presented to our eye with its end toward us, (1/2)
— Tom Stoneham (@tomstoneham) December 16, 2014
@EarlyModPhil … which must therefore be only a point, and that is invisible. (William Molyneux, 1692, 113) (2/2)
— Tom Stoneham (@tomstoneham) December 16, 2014