Constructive Dilemma Step Validator

Validate constructive dilemma by matching two conditionals, the disjunction of antecedents, and the disjunction of consequents.

Description

Constructive dilemma combines two conditionals with a disjunction of their antecedents to infer a disjunction of their consequents.

Constructive dilemma combines two conditionals with a disjunction of their antecedents to infer a disjunction of their consequents. Each disjunction may list its operands in either order.1

The tool returns matchesRule. Interpret the result under the rule and assumptions below; an encoded premise’s truth is not independently established.

When to use Constructive Dilemma Step Validator

Use this for the following task: Validate constructive dilemma by matching two conditionals, the disjunction of antecedents, and the disjunction of consequents. Prepare the specified logical encoding before running the check or transformation.

How to use Constructive Dilemma Step Validator and understand its results

  1. 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.
  2. Enter firstAntecedent, firstConsequent, secondAntecedent, secondConsequent, premiseLeft, premiseRight, conclusionLeft, conclusionRight according to the field table, then run the tool.
  3. Read matchesRule. Use the matching rule, assignment order or nonempty-class assumptions below to interpret the result.
  4. For a false check, inspect the supplied encoding and matching rule. A well-formed false result is different from an input error.
Input fieldMeaningValue type and boundsRequirement
firstAntecedentFirst Antecedentstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
firstConsequentFirst Consequentstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
secondAntecedentSecond Antecedentstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
secondConsequentSecond Consequentstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
premiseLeftPremise Leftstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
premiseRightPremise Rightstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
conclusionLeftConclusion Leftstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required
conclusionRightConclusion Rightstring; maximum text length 100; pattern ^(?!(?:true|false)$)[A-Za-z_][A-Za-z0-9_]*$(?![\s\S])Required

Supply each conditional’s identifiers and both disjunction operand pairs. Match the antecedent pair in either order and independently match the consequent pair in either order.

P→Q, R→S, P OR R ⊢ Q OR S

The symbols and boundary conditions refer to the supplied fields and the implementation described above.

Output fieldMeaningValue type
matchesRuleMatches Ruleboolean
json
{
  "input": {
    "firstAntecedent": "p",
    "firstConsequent": "q",
    "secondAntecedent": "r",
    "secondConsequent": "s",
    "premiseLeft": "p",
    "premiseRight": "r",
    "conclusionLeft": "q",
    "conclusionRight": "s"
  },
  "output": {
    "matchesRule": 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.

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 Hypothetical Syllogism Chain Validator (P→Q, Q→R ⊢ P→R) when you need its operation: Validate a hypothetical syllogism by matching two conditional links and the claimed endpoint conditional. Choose Disjunctive Syllogism Validator (P∨Q, ¬P ⊢ Q) for the complementary operation: Validate disjunctive syllogism by matching a disjunction, a negated operand, and the remaining conclusion atom.

Background reference: Additional rules for TFL.

References

  1. Additional rules for TFL — forallx Calgary, Open Logic Project

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