🗣️ Logic 101: Lesson 6: Ad Hominem (Against the Person)

🗣️ Logic 101: Lesson 6: Ad Hominem (Against the Person)

An Ad Hominem fallacy happens when someone attacks the person making an argument instead of addressing the argument itself.

Arguments are built from:

Claims

Factual Evidence

Inferences

Conclusions

People, on the other hand, have:

Character

Circumstances

Actions

When someone commits an Ad Hominem, they ignore the reasoning and go after the person — their motives, background, or behavior — as if that alone disproves the argument.

Example:

“You can’t trust her opinion on climate change — she’s not even a scientist.”

That attacks who she is, not what she said.

The goal of this fallacy is to dismiss a conclusion by discrediting the person presenting it, rather than dealing with the actual logic or evidence.

In short:

Attack the argument → Reasoning

Attack the person → Fallacy

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🚫 Logic 101: Lesson 5: Fallacies

Fallacies are errors in reasoning — arguments that seem logical, but actually aren’t.

They have the appearance of support, yet fail to prove their conclusion.

A fallacy makes an argument invalid because the conclusion doesn’t actually follow from the premises — even if the premises sound convincing.

In short:

A fallacy = an argument with broken logic.

It looks like reasoning, but it’s really a nonpoint — something you can dismiss before returning to real arguments.

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🔍 Logic 101: Lesson 4: Logical Properties of Statements

Every statement in logic has a truth value — true or false — but some statements are true or false by their logical form, not just by the facts of the world.

🌀 Logically Contingent (Indeterminate)

A statement is logically contingent if it could be true or false depending on circumstances.

“It’s raining outside.” ☔

True in some cases, false in others.

✅ Logically True (Tautology)

A statement is logically true if it’s impossible for it to be false.

It’s true by logic alone.

“Either it’s raining or it’s not raining.” 🌦️

Always true no matter what.

❌ Logically False (Self-Contradiction)

A statement is logically false if it’s impossible for it to be true.

“It’s raining and not raining at the same time.” 🚫

Always false by definition.

In short:

Contingent → could be true or false

Tautology → must be true

Self-contradiction → must be false

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🧩Logic 101: Lesson 3: Soundness

Once you know an argument is valid, the next question is: Are its premises actually true?

That’s where soundness comes in.

Sound = a valid argument with all true premises

Unsound = a valid argument with at least one false premise

A valid argument only guarantees that if the premises are true, the conclusion must be true.

A sound argument guarantees that the conclusion is true in reality.

Example (Sound):

All humans are mortal.

Socrates is human.

Therefore, Socrates is mortal. ✅

Example (Unsound):

All fish can fly.

Goldie is a fish.

Therefore, Goldie can fly. ❌

In short:

Validity = correct structure

Soundness = correct structure + true content

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⚖️Logic 101: Lesson 2: Validity

Validity = an argument is valid if it is not possible for all premises to be True and conclusion to be False

Invalidity = an argument is invalid if it is possible for all the premises to be True and the conclusion to be False

Valid - If the dog barks there is someone downstairs - The Dog barks - There is someone downstairs

Invalid - Most people in this class will pass with high A's - Eric is in this class - Eric will pass this class with high A's

Either - If I am a Martian I eat cadillacs - I am from Mars - I eat cadillacs

If (being from Mars) (makes you a Martian) then the argument is (valid)

If (being from Mars) (does not make you a Martian) then the argument is not valid

T

T

T

----

F

If not possible = valid

If possible = not valid

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🧠Logic 101: Lesson 1: The Basics

Logic = Study of Methods of evaluating arguments

Arguments = a set of statements, some of which are intended to support another.

Statements = a claim/assertion about the world, a denotative claim, either true or false

👉 The supporting ones are called premises.

👉 The one being supported is the conclusion.

The most important part of an argument to a logician is the quality of the relationship of the supporting statements to the conclusion.