Where is rationality in assigning functions to ministers?

( September 15, 2015, Colombo, Sri Lanka Guardian) A rational allocation of departments to ministries and subsequently such ministries to ministers may not be possible owing to political expediency. But, shouldn’t there be some modicum of rationality at least.
How does the recent allocation of functions and departments to Ministries stand up to the standard of rationality?
The recent allocation is more rational than in the past. But, there are a few aberrations. For example Minister Lakshman Kiriella is put in charge of University Education and Highways. What relationship is there between the two? Is there any relationship between the two functions? What has university education got in common with highways? The idea in rational allocation of functions is to group together functions which require the same or similar knowledge and aptitude on the part of the minister or manager. This point was made by Herbert Simon, one of the theorists in public administration. The knowledge and aptitudes to manage these two functions are poles apart. The former function would require a person who is academic oriented and has experience in dealing with academic personnel. The latter function is more related to engineering and construction and requires dealing with engineers and engineering problems. Can one expect a minister to have knowledge and aptitude in these two totally unrelated fields? Similarly, there is a ministry for primary industries along with the ministry of trade and industry. There is also a ministry of rural development along with a ministry for primary industries. Isn’t all this duplication of functions without clear demarcation of them?
What happens when functions are not clearly demarcated is that the ministers and their officials tread on each other’s toes. Then co-operation which is required in dealing with allied and related functions is undermined, which is detrimental to good administration.
But, the larger and more important issue is whether statutory organizations need to be brought under ministers at all. The original theory put forward by the Labor Party after the Second World War in response to critics of State ownership, who said such an exercise would not be conducive to efficiency; was that they were to be freed from ministerial control and allowed to function like private enterprises to ensure the freedom required for the conduct of business activity despite government ownership. Hence, they were not constituted as departments of the government with Treasury controls but as corporations fully owned by the State but under independent Boards of Directors.
If we are following this theory we should not be assigning these corporations to individual ministers for they are known to interfere if not directly at least indirectly through their influence with the Chairmen and directors who are appointed by the minister himself. So, these persons feel obliged to the ministers who appointed them and will have to tolerate and accept the influence of the ministers or face the possibility of being called upon to resign. I have seen this happen during my tenure in the public sector. So, what must be done? The suggestion was made to bring them under an organization like “TEMASEK” of Singapore.
Singapore’s Temasek model was accepted by China for the reform of its own State Owned Enterprises. Why not try it out although I have my doubts whether it will stop ministerial interference altogether. But, it may be better than the present situation.