Logic and Fallacies: Course Map from Aristotle to Engineering Solutions

“Logic is the science of the laws of correct thinking.”

Georgy Chelpanov, “Logic Textbook”

Logic begins not with Latin names and not with formulas. It begins in a routine moment: you hear a convincing phrase and try to understand whether you have enough reasons to believe it.

Course reference is moved to a separate page: logical fallacies space — 67 techniques with family graphs, filter, and search. The data there is the same as in the catalog chapter, so the reference and the course do not diverge.

Scene: wet asphalt

If it is raining, the asphalt becomes wet. The asphalt is wet. Therefore, it is raining now.

Sounds plausible, but the conclusion is not necessary: a watering truck could have passed, a pipe could have burst. We observed the consequence and quickly chose one cause. Later we will call this affirming the consequent, but the name is not important here. The main thing is to find the leap and suggest a check: look at the forecast, the sky or the neighboring street.

This is how the entire course is structured:

1. What exactly is being claimed?
2. What premises have already been stated?
3. What rule connects the premises to the conclusion?
4. Is there another case where the premises are true, but the conclusion is not?
5. How to formulate a more honest conclusion?

Three Breakages That Are Often Confused

Conclusion Does Not Follow

All club members received an invitation. Lena received an invitation. Therefore, Lena is a club member.

An invitation could have been sent to the guest. The problem is in the transition from the premise to the conclusion.

Repair: «Lena could have been part of the club, but a single invitation is not enough to establish this».

Weak Foundation

Three friends bought this phone model and are satisfied. Therefore, the model is reliable.

The transition is permissible as a cautious assumption, but the sample is too small and not randomly selected.

Repair: «My acquaintances are satisfied, but data on a larger number of owners and usage period are needed to draw conclusions about reliability».

Answer misses the question

— The report has an incorrect total. — But the report’s author always helps colleagues.

The second phrase may be true, but does not respond to the remark. This is a failure of relevance and dialogue.

Repair: first check the amount, then discuss the author’s qualities separately.

What Logic Does and Does Not Do

Logic checks the connection between thoughts. It helps:

• separate the thesis from examples and emotions;
• notice a hidden assumption;
• check whether the meaning of the word has changed;
• distinguish cause from mere coincidence;
• assess how much the data support the conclusion;
• make the conclusion weaker but more honest.

Logic does not automatically produce true facts. A flawless form may begin with a false premise:

All books can talk. This textbook is a book. Therefore, it can talk.

The transition form is valid, but the first premise is false.

Track without overload

You don’t have to read everything in order. Choose your current task:

Short practice

Walkthrough the phrase:

After I changed my phone wallpaper, things went better. The new wallpaper brings good luck.

Answer without terms:

1. What is the thesis here?
2. What observation supports it?
3. What other reasons for improvement are possible?
4. How to rephrase the conclusion without promising extra?

Possible fix: “After changing the wallpaper I noticed several fortunate events, but this is not enough to consider the wallpaper as their cause”.

Main course rule

The fallacy name does not refute the argument. Show exactly where the justification is missing, why the transition does not work, and what conclusion the data still allow to make.