@bangzoom9 Because it is a sufficient (but not necessary) condition for the number of beneficial soil bacteria increasing. The bacteria can increase in other ways.

However, because that is a necessary outcome of mixing plant material into garden soil, if it has not happened, then the plant material could not possibly have been mixed in.

So a similar rule to Negative Comparatives in that it opens the door to multiple possibilities as opposed to one clear answer?

@mrcarrillo327 Yes. Or, if you compare this formula to an addition problem, then it means "equals." As in:

2

+2

------

4

Or, A--->B + xA = xB.

Differentiating this argument form with mathematical comparisons rather than English ones may help you prioritize a form's validity over its content! :)

The plans for a building cannot be "true" or "untrue." They can, however, be structurally sound (valid) or structurally unsound (invalid).

Now, I tell you I'm going to build a house in Wonderland. I show you the blueprint. It is mathematically and structurally perfect—i.e., valid. If Wonderland were real, it would work flawlessly. And that validity is totally irrelevant to the "truth" of my premises, being that Wonderland is a real place I can build a house in.

@MWise Because most other recipes could be easier to follow for most people, or easier to follow for everyone.

@IvyBurt It's like putting a puzzle together by starting with the corners. Putting the center together first would make the picture come into focus more quickly, but there's a higher likelihood you'll get confused in the process. The corners take longer, but you're establishing the structure so it's easier the put the picture together later.

Realistically, if you read this sentence on the test, you'd probably include hurricanes. But that isn't the actual subject-noun, and the purpose of this exercise is just to give you practice in differentiating the two so that you'll have an easier time doing it with really complex sentences later on, where you might actually need to strip a phrase down to its barest essentials in order to put it back together.

@molebag In the LSAT, assumption questions are generally framed as "What is the assumption required to make this work?" Not, "is the assumption you're making true or false?" So, for the purposes of this exercise, we can assume the assumption is always true, in the same way the premise is always true. That's what makes it an "invisible premise."

Questions that ask "Which of the following would weaken the argument?" might touch on false assumptions.

In either case, for the purposes of the LSAT, you'll know which way you're supposed to assume.

@AnthonyAddario That sounds right. I think you'd have to add a few extra steps to make the conclusion work. "Tigers are kind of mammal which are more likely to attack and maim humans than not. Any animal that is more likely to attack a human than not would not be a suitable pet. Therefore, not all mammals are suitable to keep as pets." No wiggle room.

@DeclanSander No. In the "game" of the LSAT, you need to imagine each question exists in its own world which you know nothing about. We know that in our world, most 80-year-olds own or have owned cars, and that many of them are capable drivers. We can then assume you're probably one of those capable people.

But that information doesn't exist within the world of the question. For all we know, being 80 and being ready to buy a car are two completely unrelated ideas. Moreover, we don't know if you specifically are one of the 80-year-olds who is ready to buy a car. It has as much relevance as the P+C of "I am blond. Therefore, I should buy a coffee."

Here would be a valid argument in the world of the LSAT: "I am 80 years old. Anyone between the ages of 16 and 85 years old is ready to buy a car. Therefore, I am ready to buy a car." Why? Because there is a direct link between one fact (you are 80) and another (you are ready to buy a car). Moreover, that link is definitive. Not just "some people" are ready—anyone who meets that criteria is.

TL;DR: you need to roleplay as an incredibly pedantic alien in order to determine what counts as a valid argument in the LSAT.