I can't speak to the issue of writing books or designing cars. They are another case altogether. I can speak better about making art as that is what I'm trained for and practice in.
I have not said that there should be, or even could be, no thought whatsoever when painting, only that when you are consciously giving yourself directions as you are painting, it can interrupt the flow or progress of the actual application of paint. It can be more difficult to concentrate on the visual aspects of painting when you are moving into the "cognitive mode" to tell yourself what to do next. Much of how you paint should be automatic, engrained in your fingers from long practice and training so that you can concentrate on the visual aspects more which do not always require thought. Hence my admonition to feel more and think less when painting. When I am painting from the imagination, i.e. landscapes, small figures, etc., I have to use my "cognitive mode" or thought processes much more to determine what something would look like if I could see it first hand, i.e. the shape, color, value of every tree, item of clothing, building, cloud, etc. in the picture as I cannot see it first hand from life. I use reference sketches from life when possible and sometimes refer to historical sources to get information to tell me what should be there and what it should look like. At some point, however, you have to stop thinkng when you are actually applying the paint, designing or other purely visual operations or else you cannot physically paint. It's like trying to consciously tell each foot how to move forward so that you can walk, and this is for much of the painting time when you are trying to get the shape, value, color, texture, etc. of the objects in the painting.
I don't think that I have any "hidden premises" here that are "not supported by the facts" only first hand experience and training that has taught me this. Sometimes when you paint, you don't always have the luxury of time, for a variety of reasons, to be as careful as you might want and get it "just right". Sometimes in the course of working it over and over to get it just right, the painting becomes overworked and "stiff" and you may want to keep to your original version if it serves your purpose better and is still convincing.
While I do not go out of my way to add inaccuracies (the habit to paint or draw what I see accurately is thoroughly engrained from training), it's the subtle "errors" in value, color, draftsmanship etc. that tells the viewer that this painting was done by hand with the perceptions and judgement of a person. I don't know what the psychology of it is, but there is something in people that wants to see the "human element" which is revealed, I think in part, by the painting not being "mechanically accurate" like an architectural drawing. This is a very subtle thing that most people may not consciously see but may be picked up nevertheless.
There is also the perception of movement that many people find attractive in a painting. This could be the movement of some object in the picture, the apparent movement of the painter in painting the picture or the easy movement of the eye through the painting, which is denoted better without the extreme finish, "perfection" and with an eye to the flow of the linear rhythms. Renaissance figure drawings and paintings are often incorrect in parts of their anatomy but the "inaccuracies" are made to strengthen the unifying lines or rhythms that help to move the eye about, create unity and give the impression of movement, power or whatever they are trying to express. What little they lose in "mechanical accuracy" or "truth to nature" is amply rewarded in the painting's clearer intent. This is simply part of the "artistic license." Even those objects that are at rest can benefit by the flow of line to create unity.
It is this willingness of the Renaissnace painters and others to accept "dither" to achieve the feeling of motion, greater clarity of intent, greater unity of line, and ease of moving the eye around the composition, etc. that helps make their work enduring and which can aid us in our present work as artists. Perhaps it's this difference in painting approach that makes some people feel uncomfortable with "atelier styled" painting while applauding the Renaissance painters.
I apologize if I've rambled off topic. All of these things are interrelated and need to be said.
"Nature wants (needs) cooking." -- William Gilpin 1796
Hope this helps.
