Denying the Antecedent Fallacy Flag Detector
Detect the denying-the-antecedent pattern with distinct identifier atoms and explicitly negated terms.
Description
Denying a conditional’s antecedent does not generally establish denial of its consequent.
Denying a conditional’s antecedent does not generally establish denial of its consequent. The consequent may hold for another reason.1
The tool returns matchesFallacy. Interpret the result under the rule and assumptions below; an encoded premise’s truth is not independently established.
When to use Denying the Antecedent Fallacy Flag Detector
Use this for the following task: Detect the denying-the-antecedent pattern with distinct identifier atoms and explicitly negated terms. Prepare the specified logical encoding before running the check or transformation.
How to use Denying the Antecedent Fallacy Flag Detector and understand its results
- Prepare the requested Boolean values, complete truth-table rows, or identifier atoms. An atom is a name such as p or premise_1, not a natural-language sentence.
- Enter antecedent, consequent, negatedPremise, negatedConclusion according to the field table, then run the tool.
- Read matchesFallacy. Use the matching rule, assignment order or nonempty-class assumptions below to interpret the result.
- For a false check, inspect the supplied encoding and matching rule. A well-formed false result is different from an input error.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| antecedent | Antecedent | string; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S]) | Required |
| consequent | Consequent | string; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S]) | Required |
| negatedPremise | Negated Premise | string; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S]) | Required |
| negatedConclusion | Negated Conclusion | string; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S]) | Required |
Supply conditional identifiers and the atoms represented by the negated premise and conclusion. Flag the pattern only if the conditional atoms differ and the supplied negated atoms match P then Q.
P→Q, NOT P ⊢ NOT Q is a fallacy for distinct independent atoms The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| matchesFallacy | Matches Fallacy | boolean |
{
"input": {
"antecedent": "p",
"consequent": "q",
"negatedPremise": "p",
"negatedConclusion": "q"
},
"output": {
"matchesFallacy": true
}
}Limitations and assumptions
Operands are case-sensitive identifier atoms, not complete expressions. The tool does not parse a proof or determine whether the premises are true. A false flag only means this particular fallacy pattern was not matched.
The supplied encodings must represent the intended propositions or classes. No natural-language parsing or assessment of empirical premise truth is performed. Malformed input gives a tool error rather than a logical false result.
Alternative or Complementary methods
Choose Modus Tollens Inference Step Validator (P→Q, ¬Q ⊢ ¬P) when you need its operation: Validate a modus tollens step by matching the identifiers negated in its premise and conclusion. Choose Affirming the Consequent Fallacy Flag Detector for the complementary operation: Detect the affirming-the-consequent pattern with distinct identifier atoms.
Background reference: Additional rules for TFL.
References
-
Additional rules for TFL — forallx Calgary, Open Logic Project
Similar or alternative tools
- Modus Tollens Inference Step Validator (P→Q, ¬Q ⊢ ¬P)
Validate a modus tollens step by matching the identifiers negated in its premise and conclusion.
- Affirming the Consequent Fallacy Flag Detector
Detect the affirming-the-consequent pattern with distinct identifier atoms.