Hi utpalbarman,
Thanks for the questions! Let's look at both:
Tu Quoque: This is in the LRB already, as it is a form of Ad Hominem/Source argumentation. Essentially, the second speaker tells listeners to ignore what the first speaker said because it is claimed the first speaker acts inconsistently with the statements they made. In fact, the very first example given on page 508 in the Source Argument section is exactly this flaw. Remember, most of the time we don't use formal names for the flaws because it makes them harder to understand for most people. Tu Quoque is just one variant of an Ad Hominem, and calling the entire group "Source Arguments" makes them far easier to remember for most students.
No True Scotsman: This is also actually in the LRB, because this is a variant of a circularly reasoned argument. Essentially someone is saying you aren't a true Scotsman because a true Scotsman wouldn't do that, which means the definition in the premise is assumed true and then used to prove the conclusion, which relies entirely on the premise definition. This definitional aspect being repeated is the basis for the flaw here.
You might ask why don't I talk about this specifically named flaw in the LRB, and that's because they hardly ever do it on the LSAT. And also, it's fairly easy to recognize, and there's a point in the book where you simply can't run down every single variant of fallacy that ever existed
Please let me know if that helps. Thanks!
