# Circulus in Probando (Circular Reasoning)

”One might think the fallacy would be so obvious that no one would ever commit it, but that is not the case.” - Irving M.

Date: 2026-07-04
URL: https://logic.darthdemono.com/Fallacies/Circulus-in-Probando-(Circular-Reasoning)
Tags: Fallacy

---

#### _”One might think the fallacy would be so obvious that no one would ever commit it, but that is not the case."_ - Irving M. Copi, Carl Cohen, and Kenneth McMahon, _Introduction to Logic_, 14th Edition, 2014, 140.

## Etymology:

- The Latin term "_Circulus in Probando_" translates to “a circle in proof”.
## Definition:

- When the beginning and the end of a chain of proof are the same, it's called the Circular Reasoning Fallacy.
- The argument circles back on itself without providing independent explanation/evidence for its claim.

![[Circular Reasoning.png|center md]]

<h6 style="text-align: center;">Avoiding the Pitfalls of Circular Reasoning by ASAT</h6>

## Details:

Circular Reasoning is an informal fallacy. The argument goes: X happens due to Y, Y happens due to Z, and Z happens due to X. This is a circular argument.

## Types of Circular Reasoning:

1. **Petitio Principii (Begging the Question)**: Happens when the premise already includes the conclusion.
    1. **Restating the Conclusion**: Restating the conclusion but using different words to make it sound more reasonable.
        - **Example:**
            - **X:** “A taxation system of that kind will never succeed, because it cannot work.”
        - **Counter**:
            - **Ask for an explanation:** “Can you please explain why the taxation system cannot work?”
    2. **Assuming Unstated Premises**: Relying on premises that are unstated or unexplained.
        - **Example:**
            - **X:** “We must reduce taxes to improve the economy.”
            - **Y:** “How will reducing taxes improve the economy?”
            - **X:** “Because the best way to improve the economy is to reduce the taxes.”
        - **Counter**:
            - **Challenge the unexplained premise:** “Is there any data that supports what you are stating?”
    3. **Loaded Question**: Assumes something to be true without explaining why.
        - **Example:**
            - **X:** “Have you stopped beating your wife?”
            - (Assumes you are beating your wife, and either answer “Yes” or “No” will mean that you have beaten your wife.)
        - **Counter:**
            - **Directly address the assumption:** “I do not condone any violence in my relationship.”
            - **Highlight the flaw:** “You are assuming that I’m beating my wife without any evidence. It is childish to use such Loaded Questions.”

2. **Petitio Principii (Circular Definition)**: Term which is defined using the term itself.
    - **Example:**
        - **X:** “A woman is someone who identifies as a woman.”
        - (The definition needs to be independent without using the term itself; here, "woman" is used as a term for defining "woman.")
    - **Counter:**
        - **Highlight the flaw:** “You cannot use the term itself to define a term. This is what we call a Circular Definition fallacy.”
        - **Use a proper and clear definition:** “Sorry, but a woman is an adult human female.”
        - (One should use both of these counters to properly respond.)

3. **Circular Explanation**: Restates the original assertion without adding anything new.
    - **Example:**
        - **X:** "Why do we need laws?"
        - **Y:** "Because without laws, we would have anarchy."
        - **X:** "What is anarchy?"
        - **Y:** "It is a situation where there are no laws."
    - **Counter:**
        - **Ask for an explanation:** “Can you explain how the lack of laws leads to anarchy?”

1. **Assuming the Conclusion**: As the name implies, it's when the conclusion is assumed already.
    - **Example:**
        - **X:** “Lying is wrong because it's wrong to lie.”
        - (No explanation has been given on why it is wrong; it just assumes that lying is wrong.)
    - **Counter:**
        - **Ask for an explanation:** “Can you explain why exactly lying is wrong?”

## Why?
### Why is it a Fallacy?
The reason why Circular Reasoning is a fallacy is because it is fallacious. Nah, I'm kidding. It is a fallacy because to prove something or to disprove it, you need independent confirmation/evidence. Circular Reasoning repeats its own claims without external verifiable confirmation. It creates a circular chain where it tries to validate itself but fails. Similar to attempting to lift yourself by pulling your own leg, nothing happens, and at worst, you fall down.

### Why would someone do this?
Different reasons exist for using various types of circular reasoning fallacies.

- **Lack of Knowledge on Logic:** Some fallacies, like Assuming Unstated Premises or Restating the Conclusion, might come from a lack of understanding of logical reasoning.
- **Deception:** Loaded questions are used to deceive by assuming something negative about the proponent.
- **Making a Point Without Knowledge:** Circular Explanation and Assuming the Conclusion fallacies can happen when a proponent tries to make a point or wants to say something without any knowledge.

## When Is It Fair to Use?
Never, that’s it, never.