Fundamentals of Critical Thinking and Essay Preparation — GRE Analytical Writing GED Study Notes

Chapter 1

Fundamentals of Critical Thinking and Essay Preparation

Course: Gre
Subject: Gre Analytical Writing
Chapter: Fundamentals Of Critical Thinking And Essay Preparation

Introduction: Evaluating the Logic Behind Arguments

Have you ever watched a movie where children discover their parents are actually aliens from another planet? The kids often think their parents' advice is so strange that it must come from another world! While most parents aren't from outer space, the advice they give deserves to be examined and evaluated.

In this lesson, we'll learn how to evaluate reasoning—a critical thinking skill that helps us determine whether someone's argument makes sense. We'll use a funny example of parental advice to understand the process step by step.

Real-Life Example: A Note in a Lunchbox

Little Johnny opens his lunchbox at school and finds a note from his mom:

"Always wear clean underwear; you might be in an accident and the doctors will think you are a dirty person."

Johnny thinks this advice is so weird that his mom must be from another planet! But before jumping to conclusions, let's use proper reasoning evaluation to determine if Mom's advice is reasonable.

Steps to Evaluate Reasoning

Step 1: Identify the Conclusion

The conclusion is the main claim being made—what the author wants you to believe.

In Mom's note:

Conclusion: "Always wear clean underwear"

Step 2: Identify the Stated Premise

The premise is the reason given to support the conclusion. There may be more than one premise.

In Mom's note:

Stated Premise: "You might be in an accident and the doctors will think you are a dirty person"

Step 3: Identify Any Unstated (Implied) Premises

An implied or unstated premise is something that isn't directly written but must be true for the argument to make sense. These are the hidden assumptions behind the reasoning.

In Mom's note, what must be true for her advice to hold up?

Implied Premise: "Clean underwear actually stays clean after an accident"
Implied Premise: "Doctors will check your underwear during an accident"
Implied Premise: "Doctors care about the cleanliness of your underwear"
Implied Premise: "Being thought of as a dirty person is a terrible outcome"

These unstated assumptions reveal potential weaknesses in the argument!

Step 4: Evaluate Whether the Premise Supports the Conclusion

This is the most important step. We must determine if the premises (both stated and unstated) actually provide reasonable support for the conclusion.

There are two main ways to evaluate this connection: inductive validity and deductive validity.

Inductive Validity: Making Probable Conclusions

Inductive validity asks: Based on the premises, is it reasonable to believe the conclusion? With inductive arguments, it's possible (but unlikely) that the premises are true and the conclusion is false. Inductive reasoning deals with probability and likelihood.

Key Features of Inductive Arguments:

Conclusions are probable, not certain
The premises make the conclusion likely, but don't guarantee it
We use inductive reasoning every day to make predictions

Example of Inductive Validity:

This is inductively valid because:

The premise provides strong evidence for the conclusion
It's extremely likely (though not 100% certain) that the conclusion is true
We can't prove tomorrow will happen, but all evidence suggests it will

Testing Mom's Argument Inductively:

Premise: "You might be in an accident and doctors will think you are a dirty person if your underwear is dirty" Conclusion: "Always wear clean underwear"

Is this inductively valid?

How likely is it that you'll be in an accident where doctors see your underwear?
How likely is it that doctors would care about or judge your underwear cleanliness?
How likely is it that doctors would think you're a "dirty person" based on underwear?

The inductive support seems weak—the premises don't make the conclusion very probable.

Deductive Validity: Logical Necessity

Deductive validity asks: If the premises are true, must the conclusion also be true? A deductively valid argument is structured so that it's impossible for the premises to be true and the conclusion false.

Key Features of Deductive Arguments:

If premises are true, conclusion MUST be true
The argument structure guarantees the conclusion
Truth of premises + valid structure = sound argument

Example of Deductive Validity:

This is deductively valid because:

If both premises are true, the conclusion cannot be false
The logical structure forces the conclusion

Testing Mom's Argument Deductively:

To test deductively, we need to see if the conclusion necessarily follows from the premises.

Premise: "You might be in an accident and doctors will think you are a dirty person if your underwear is dirty" Conclusion: "Always wear clean underwear"

Does the conclusion HAVE to be true if the premise is true? No—there are many situations where:

You never have an accident
You have an accident but doctors don't see your underwear
Doctors see your underwear but don't care
Doctors see your underwear but don't think you're a dirty person

Therefore, the argument is NOT deductively valid. The conclusion doesn't necessarily follow.

Summary: Evaluating Mom's Argument

Verdict: Mom's advice might be questionable! While wearing clean underwear is generally a good hygiene practice, her reasoning doesn't hold up to careful evaluation.

Practice: Apply the Steps

Try evaluating this piece of advice: "Eat your vegetables because they're good for you, and if you don't, you'll get sick."

Step 1: Identify the conclusion

"Eat your vegetables"

Step 2: Identify stated premises

"They're good for you"
"If you don't, you'll get sick"

Step 3: Identify unstated premises

"Not eating vegetables directly causes sickness"
"There are no other factors that prevent sickness"
"The person will definitely get sick without vegetables"

Step 4: Evaluate the support

Inductively: Is it likely that not eating vegetables leads to sickness? Possibly, but many factors affect health.
Deductively: Does the conclusion necessarily follow? No—many people don't eat many vegetables and don't get sick.

Key Takeaways

Conclusion: The main claim someone wants you to believe
Premise: The reason(s) given to support the conclusion
Unstated premise: Hidden assumptions that must be true for the argument to work
Inductive validity: The premises make the conclusion probable (but not certain)
Deductive validity: If premises are true, the conclusion MUST be true
Evaluating reasoning helps us think critically about arguments, not just accept them at face value
Even reasonable-sounding advice may have weak logical support