Pilpul (Hebrew: פלפול, loosely meaning "sharp analysis") refers to a method of studying the Talmud through intense textual analysis in attempts to either explain conceptual differences between various halakhic rulings or to reconcile any apparent contradictions presented from various readings of different texts. Pilpul has entered English as a colloquialism used by some to indicate extreme disputation or casuistic hairsplitting. This usage has especially fallen into use among critics of Haredi Jews, impugning their Talmud study as non-productive.
The requirement for close derivation of the conceptual structures underlying various Jewish laws, as a regular part of one's Torah study, is described by Maimonides (Yad HaChazakah, Sefer Madda, Laws of Torah Study, 1:11) as follows:
|“||A person is obligated to divide his study time in three: one third should be devoted to the Written Law; one third to the Oral Law; and one third to understanding and conceptualizing the ultimate derivation of a concept from its roots, inferring one concept from another and comparing concepts, understanding [the Torah] based on the principles of Torah exegesis, until one appreciates the essence of those principles and how the prohibitions and the other decisions which one received according to the oral tradition can be derived using them....||”|
In the narrower sense, pilpul refers to a method of conceptual extrapolation from texts in efforts to reconcile various texts or to explain fundamental differences of approach between various earlier authorities, which became popular in the late fifteenth and early sixteenth centuries: its founders are generally considered to be Jacob Pollak and Shalom Shachna.
Many leading rabbinic authorities harshly criticized this method as being unreliable and a waste of time, and it is regarded by some as having been discredited by the time of the Vilna Gaon. A frequently heard accusation is that those who used this method were often motivated by the prospect of impressing others with the sophistication of their analysis, rather than by a disinterested love of truth. These students typically did not apply appropriate standards of proof in obtaining their conclusions (if any), and frequently presupposed conclusions that necessitated unlikely readings of "proof-texts". As such, pilpul has sometimes been derogatorily called bilbul, Hebrew for "confusion".
The Maharal in a famous polemic against Pilpul (Tiferet Yisroel, pg. 168), states that "It would be better to learn carpentry or another trade, or to sharpen the mind by playing chess. At least they would not engage in falsehood, which then spills over from theory and into practice..." 
On the other hand, many authorities[who?] argued that there is a legitimate place for genuine pilpul as being reliable and even central to Talmud study, provided that traditional standards of proof were applied rigorously.
In the late eighteenth and nineteenth centuries, pilpul in this narrow sense was largely superseded by the analytic methods pioneered by the Lithuanian school, in particular the Brisker derech. However, many people consider these methods too to be a form of pilpul, though the practitioners of the analytic method generally reject the term. Before World War II, both the old and the new kinds of pilpul were popular among Lithuanian and Polish Jews. Since then, they have become prominent in most Ashkenazi and many Chassidic yeshivas.