LogicLesson 2 of 2

Necessity, Sufficiency & Applied Logic

Taught in English

Questo esame si sostiene in inglese: le lezioni e le domande sono in inglese. L'interfaccia resta in italiano.

100%

Hold ⌘ / Ctrl and scroll to zoom

SubjectLessonDone

Drag to pan · ⌘/Ctrl + scroll or pinch to zoom · tap a node for detail · +/− to expand a branch

Key formulas

Inclusion-Exclusion (Venn)

|A∪B|=|A|+|B|−|A∩B|Both=|A|+|B|−|those with at least one|

Part 1 of 1

Affirming the Consequent & Venn

Affirming the consequent is invalid: P→Q and Q is true does NOT prove P.

The correct inference from "Q is true" alone: nothing about P. P might or might not be true.

Venn diagram procedure

Label circles A and B
Write the total and "neither" count
|A ∪ B| = total − neither
|A ∩ B| = |A| + |B| − |A ∪ B|

Always draw it. Always.

Worked example

"Interest rates drop → equity rises." Equity rose today. Does NOT mean rates dropped — other causes exist. This is affirming the consequent. Venn: 40 people, 25 English, 18 French, 8 neither. |E∪F| = 32. Both = 25+18−32 = 11.

Unlock Full Lesson & Timed Practice Drills

Gain full lifetime access to all 2 lessons in Logic & Reasoning, interactive MindMaps, step-by-step solved questions, and full timed mock exams for Bocconi MSc Admission Test.

Unlock Full Bocconi MSc Admission Test Pass (€29)

Deductive Reasoning & Syllogisms Try a mock exam

Necessity, Sufficiency & Applied Logic

Affirming the Consequent & VennAffirming the Consequent & Venn

Venn diagram procedure

Unlock Full Lesson & Timed Practice Drills

Necessity, Sufficiency & Applied Logic

Affirming the Consequent & VennAffirming the Consequent & Venn

Venn diagram procedure

Unlock Full Lesson & Timed Practice Drills

Affirming the Consequent & Venn

Affirming the Consequent & Venn