I found this section on Aggadata in the Introduction to Nezikin in the Soncino Talmud. It is by Chief Rabbi J. H. Hertz and is clearly written to remove any charges of anti-Christian sentiment from the Talmud (if you read the entire piece it is clear that is a major issue for him - this was the first time that the entire Talmud was translated into English).
But it is still shocking to see what he writes - I suspect that if a Chief Rabbi today would claim that Aggadata is simply "beautiful old stories" or that "certain Jewish commentators are fools" they would get in trouble.
But Chief Rabbi Hertz was the Chief Rabbi during the period from before WWI until just after WWII. Times were different. The challenges and issues facing Jewry, and the levels of anti-semitism were entirely different. And he felt that this type of approach was the most effective one.
The Talmud itself classifies its component elements either as Halachah or Haggadah. Emanuel Deutsch describes the one as emanating from the brain, the other from the heart; the one prose, the other poetry; the one carrying with it all those mental faculties that manifest themselves in arguing, investigating, comparing, developing: the other springing from the realms of fancy, of imagination, feeling, humour:
Beautiful old stories,
Tales of angels, fairy legends,
Stilly histories of martyrs,
Festal songs and words of wisdom;
Hyperboles, most quaint it may be,
Yet replete with strength and fire
And faith-how they gleam,
And glow and glitter!
as Heine has it.
Halachah, as we have seen, means ‘the trodden path’, rule of life, religious guidance. To it belong all laws and regulations that bear upon Jewish conduct. These include the ritual, the civil, criminal, and ethical laws. Everything else is embraced under the term Haggadah; literally, ‘talk’, ‘that which is narrated’, ‘delivered in a discourse’. This again can he subdivided into various groups. We have dogmatical Haggadah, treating of God’s attributes and providence, creation, revelation, Messianic times, and the Hereafter. The historical Haggadah brings traditions and legends concerning the heroes and events in national or universal history, from Adam to Alexander of Macedon, Titus and Hadrian. It is legend pure and simple. Its aim is not so much to give the facts concerning the righteous and unrighteous makers of history. as the moral that may be pointed from the tales that adorn their honour or dishonour. That some of the folklore element in the Haggadah, some of the customs depicted or obiter dicta reported. are repugnant to Western taste need not be denied. ‘The greatest fault to be found with those who wrote down such passages. says Schechter, ‘is that they did not observe the wise rule of Dr Johnson who said to Boswell on a certain occasion, “Let us get serious, for there conies a fool”. And the fools unfortunately did come, in the shape of certain Jewish commentators and Christian controversialists, who took as serious things which were only the expression of a momentary impulse. or represented the opinion of sonic isolated individual, or were meant simply as a piece of humorous by-play, calculated to enliven the interest of a languid audience.’ In spite of the fact that the Haggadah contains parables of infinite beauty and enshrines sayings of eternal worth, it must be remembered that the Haggadah consists of mere individual utterances that possess no general and binding authority.