Guides, regulations, commandments, laws etc whatever you define it is just a way we solve problems. They are good because they are stipulated, documented, and are available to us on a ready made form. We can read, use, and translate them to relate, question, and formulate things.
scenario; eggs and chicken: The question is who is old between the two? The answer here depends on our understanding of eggs and chicken. Chicken is older than egg but is that not where chicken comes from anyway and where does chicken comes from? If you ask such question number of times, participants involve gets confused that they change their answer from one to the other depending on time and how they are asked. This is why rules are so important to guide us through such complications. Programmers(computer programmers) are good example to help solve this problems.
scenario 2; Finding GDP of a country: Mathematicians are the immediate people to help solve this problem because they have the logic and know how. You will think that solving that problem is easy. That is true but, it usually depends on your knowledge of finding unknown - imagination and assumptions. The answer to most time is based on number of people and businesses earning in a particular group of people e.g. country, district, state etc. They always missed out on unlawful earnings e.g. handout e.g. criminal money like drugs etc. This are big earning of a country but because they are outside the law we need to assume that they exist because that same money is used for development, doing lawful businesses etc. We also fail at constants of earnings because earning fluctuates from high to low based on situations e.g. out breaks, booms etc. Those are irregular situations hence, most people fail to predict them hence leading to wrong official number to the public.