Principles and rules.
Why are there so many detail and so many particulars in Torah study? Are they all directly from Sinai or were they derived by some method of interpretation?
And G-d spoke to Moshe upon the mountain of Sinai , saying…
What is the meaning of Shemittah at Sinai? Are not all the commandments spoken from Sinai? However it is to indicate that just like Shemitah was given with all of its principles, particulars and details from Sinai  so were all the commandments given with principles, particulars and details at Sinai (Toras Kohanim, beginning of Behar).
This view appears to be that of R. Akiva in Zevachim 115b.
R. Akiva says: Principles and particulars were given at Sinai and reviewed at the Tent of Meeting and repeated a third time at Arvos Moav.
R. Ishmael says: Principles were said at Sinai and particulars were said at the Tent of Meeting.
The passage in Toras Kohanim appears to be saying that every commandment was transmitted to Moshe with its general principles as well as every detail. If so, however, we must ask about the need for details. Would it not be adequate to give him the principles from which the details could be derived? Even if only some particulars could have been so derived, why would they need to be given? Alternatively, if all the details and particulars were explained at Sinai, what need would there be for principles?
It may be instructive to stop for a moment and consider the structure and method of Halachic discourse.
Traditional Judaism is a covenantal system of laws and customs based on Divine Will as revealed at Mount Sinai to the Children of Israel. To the uninitiated it may appear to be a casuistic system of law. Classic casuistry did not apply principles in a deductive or inferential fashion but, in common with the classic discipline of rhetoric, drew eclectically from the vast storehouse of classical writings and focused argument on cause and effect, before and after, possible and impossible, greater and less and the specific circumstances of a case. Those not intimately acquainted with Talmudic argumentation may initially perceive it similarly, and if so, the complaint voiced above would have been justified.
In fact, however, Halachic reasoning draws essentially and substantially on clarification and distillation of principles from the mass of precedent and text. It is, what is known as rule and principle based system; in consequence, argumentation about and definition of principles is what it is all about. It is therefore similar to any other legal or moral theory in use in modern world. 
To define the problem farther, while there are certainly frequent references to Sinaitic tradition in the Talmud, there are also numerous passages that appear to indicate that certain laws were 'derived' from Biblical verses at one time or another. This then requires us to delineate the relationship between derivation and tradition.
Among the medieval authorities that took up this question, there emerged two schools of thought. One saw Talmudic evidence as demonstrating that Talmudic material was transmitted directly, teacher to student, from one head of academy to another, detail after detail. Nothing, no matter how trivial, was innovated, except those Rabbinic enactments that are clearly and unambiguously so identified. This view is expressed by R. Sherira Gaon in his Letter, R. Abraham ben Daud in the introduction to the Book of Tradition, R. Nissim Gaon in Mafteach L'Manuelei Hatalmud, and R Saadiah Gaon in his numerous anti-Karaite works. To quote a representative passage from Sefer Hakabbala: "… teachings of the rabbis of blessed memory, namely, the sages of the Mishna and Talmud, have been transmitted; each great sage and righteous man having received them from a great sage and righteous man, each a head of academy and his school, as far back as the men of the Great Assembly, who received them from the prophets of blessed memory. Never did the sages of the Talmud, and certainly not of the Mishna teach anything, however trivial of their own invention, except for enactments which were made by universal agreement in order to make a hedge around the Torah " . How could then controversy and disagreement exist among Talmudic Sages? It is because some details of particular laws were forgotten in the course of exile due to relentless persecutions. The purpose of derivations then is to restore these details but never the major principles.
We must conclude from examining the passage in Toras Kohanim and Zevachim that one Tannitic opinion believes that it is not possible to derive rules reliably from principles. Human beings do apply principles differently and often disagree with each other's translation of principles into rules. It is therefore, necessary to provide revealed rules form the outset, both to minimize disagreement and dispute and to demonstrate how principles are to be practically interpreted to yield rules. This view is expressed best by the Ramban in the introduction to his commentary to Brochos, where he draws a distinction between sciences that employ experiments and the method of Talmudic argument. The former can yield definitive proof but the latter only a presumption of being right. In this view, not only rules alone were given at Sinai but every possible range of opinion and every Halachic possibility were disclosed to Moses .
In modern times, R. I.A. Halevy in Dorot Harishonim championed this view .
Maimonides presents a different account of the history of religious law and its transmission in the Introduction to the Mishna and relevant passages of his other works. He claimed that in addition to received laws the Sages derived new interpretations with the authority that the Torah has granted them. In this they made use of the thirteen rules of interpretation, commonly accepted legal principles and received definitions of terms , and disputes and controversies only occur in regard to these newly derived laws. Rambam wrote in the Introduction to the Mishna : " and likewise each person, as he heard and according to his ability, wrote for himself some of the explanations of Torah and its laws and things that became innovated in every generation - laws that they did not learn by tradition but they derived with one of the 13 techniques (of interpretation) and to which the High Court assented. So it went at all time periods."
This is why there were no disagreements before the students of Hillel and Shammai, not having learned sufficiently well from their illustrious teachers, attempted to carry forward the tradition . Here too, disagreements resulted when later generations have lost some of the acumen and grounding of the previous ones. "… for when two people are identical in understanding and in study and knowledge of the principles from which they learn, there will not happen disagreements between them as to what they learn by the use of one of the principles of interpretation, and if there are disagreements, they will be few, as we never found disagreements between Shammai and Hillel except in a few laws, for their ways of study were similar and also the correct general assumptions that were held by one were also held by another". Rambam believes that logic alone can establish all details and in this he seems to follow R. Ishmael. Thus, principles were given at Sinai and particulars, were derived under Divine Guidance, in the Tent of Meeting.
In modern times, R. Meir Leibush Malbim subscribed to the position that derivations created law rather than simply restored them .
We conclude then that the disagreement among Tannaim may be, in fact, revolving around the central question of whether details of new laws are derived or transmitted and secondarily around the ability of logic to reliably and reproducibly bring rules out of principles. This very question divided the Rishonim as well and it remains one of the central controversies about the relationship of innovation and tradition.
1 Principles in Shemos 23:10-11; details in Parshas Behar.
2 For an extended discussion of this point, see M. Levin, I. Birnbaum, Jewish Bioethics, Journal of Medicine and Philosophy 25(4), 468-484, 2000
3 R, Sherira Gaon (Ch.2 of the Iggeret) follows the same view but he introduces another strand of thought. He suggests that in the years prior to writing down of the Mishna, each Tanna taught and organized the material that he had received in his own way. At the time of the Mishna there came to exist various formulation of the same material, each phrased and expressed in a somewhat different language and phrasing. "Some taught general rule; others added detail; and others expanded and offered many examples and analogies." Presumably, this itself may have led to different understandings and interpretations of the same original traditions. Rabbi elected to follow the formulations of R. Akiva and his students while relegating other collections to "external" status; this explain preponderance of certain names in the Mishna and its focus on citing later Sages.
4 See Ramban to Deut 11:17. This topic is tangential to our discussion; suffices to say that it is the students of the Ramban, Ritvo and Ran who gave voice to this view. It appears that if you don't believe that logic alone can guide one to the truth, something else must substitute. For the role of Ruach Hakodesh in choosing the 'correct' interpretation, see the above Ramban and Netsiv's introduction to Sheiltos, Igrot Moshe, introduction; and Chazon Ish, Kovets Inyanim.
5Dorot Harishonim I, 5, p. 487. R. Halevy maintains that rabbinic derivations do not create laws but serve solely to support and base received laws.
6 Such as torts, damages, etrog, sukah and the like.
7 In modern philosophy such an approach is called the coherence theory of truth - the truth is that which coheres best with the pre-existent premises and methods of deduction.
8 Ayelet Hashachar, Introduction to Hatorah Vhamitsva on Leviticus.