It just came to my mind, currently if one wants to obtain an academic degree one must to do a thesis. This is a widely accepted method to prove the knowledge of certain academic level, sort to say. But my questions are, where this method was originated? Which historical or social circumstances originated it? Is there any philosophical background?
(note: I have no references for the below, nor am I qualified in the topic)
First of all, the premise of your question isn't quite accurate: certainly in the UK it's very common for undergraduate degrees to have no thesis requirement. But putting that aside:
I think there are parallels with other mediaeval professions, which required proof of skill in order to become a member of a guild (the professional organisation). To be a 'master' of the guild one had to produce a 'masterpiece' (the origin of that word); this has obvious parallels with the idea of a thesis proving that an individual should be admitted to a degree (remember that historically a degree is more like a rank than an award, honour or qualification).
The MA at Oxford and Cambridge is still awarded automatically to those with a BA seven years after the start of the degree, which I believe matches the time someone in a professional guild would take to become a master.
Note also that the modern doctorate is a much more recent invention than the MA.
A bit if history. The history of thesis is intertwined with the history of universities in the 12th and 13th century.. The early history of universities is not clear but with time systems develop on how information/knowledge is taught and discussed. The end (so far) result is what we have today. The written thesis is based on the fact that ideas need to be made more permanent than oral traditions. the advent of printing made wider distribution of copies possible. The first degrees were the baccaulerate and magister artium which corresponded to doctor in certain disciplines.
The thesis was originally what the word describes a thought or thinking that needed defending, which goes backs to Aristotle and Plato. As soon as writing was possible, the idea was to put the ideas down in writing and hence a written thesis was born. One has to remember that teaching early on did not necessarily occur as lectures, it could be mentioning and learned discussions. At the same time knowledge was not as structured and defined as now.
early on the teacher actually wrote the thesis and t was the students job to defend it. So the focus was less on developing knowledge but to defend a thesis with arguments and logic. During the renaissance the thesis in a form we can recognise was developed. These texts were called dissertatio (lat. development, presentation) where as the defence was named disputatio (lat. c. learned argument). From these relatively common beginnings different "cultures" developed which now are reflected in differences between countries in how a thesis is defined and defended.
Much more details can probably be added to this but the core is covered. There is no necessary connection between a degree and a thesis. Certainly not at a bachelor's leverl and it is also possible at a master's level. Differences also exist between disciplines.