Blue-Sky means having the pleasant appearance of a blue sky. A completely blue sky has no opaque objects, in other words no clouds. Similarly, Blue-Sky Thinking was considered to be empty thinking (i.e. a blue sky without clouds) and in this case without the tarnish of any ideas at all. More specifically, Blue-Sky Thinking means fanciful thinking, hypothetical, not practicable or profitable in the current state of knowledge or technical development. The use of Blue-Sky goes back to 1906, when it was used in the context of Blue-Sky securities, which are worthless securities. Those people trading in worthless securities, something that would later be referred to as junk bonds, were said to be selling “Blue-Sky and hot air” and so were called “Blue-Sky merchants.” In 1948, Blue-Sky securities indicated a bad investment or a fraud.
Blue-Sky was used in a different way in the 1920’s, in a work called Raymond Robins’ Own Story, by W.Hard, which refers to Lenin and Trotsky never giving any Blue-Sky talk. In other words, they never promised anything without the power and the will to deliver. Later, in 1956, the phrase Blue-Sky book came into being in the U.S. This type of book is a literary work which lacks any expert knowledge or specific technique. Similarly, there is a quote in the Times in 1977 regarding Blue-Sky technologies, which are those where there are no real world applications immediately apparent. So Blue-Sky carries a theme where there is nothing useful, nothing concrete or practicable. Ref: English Oxford Dictionary.
Blue-Sky Thinking is currently considered to be thinking that is not based or connected with the realities in the present moment. It allows for creative ideas where there is no restriction or limitation placed on them from current thinking or beliefs.
There is a similar usage, which is the phrase, “Thinking Outside The Box”, which means thinking creatively, freely, without restriction or conventional constraint. The origin of this is from the U.S. in the late 1960’s/early 1970’s. There is an early example in the Aviation Week & Space Technology Magazine, in July 1975, which says, “We must step back and see if the solutions to our problems lie outside the box.”
The ‘box’ represents rigid and unimaginative thinking, so out of the box is a distinct contrast. Thinking outside the box and Blue-Sky thinking essentially mean the same thing, the latter phrase being the older of the two.
These phrases described above relate to the work of Edward De Bono, a psychologist and inventor, who gave encouragement in the U.K. to find solutions from outside our normal thinking behaviour. He also coined the phrase Lateral Thinking, in 1967, and went on to develop it as a method of structured creativity.
All this given to the world of business and beyond, from a simple, pleasant sight of nature and environment.