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# Psych Research Pt 2

### Propositional Logic Forms of Arguments

Term | Definition |
---|---|

Affirming the Consequent | If P is true, then Q is true. Q is true, therefore P is true. |

Is Affirming the Consequent valid? | No; it is logically impossible to ever prove that a theory is completely true. |

Is Affirming the Consequent useful to science? | Sort of; a correct prediction can increase our belief in the theory. |

Modus Tollens | If P is true, then Q is true. Q is not true, so P is not true. |

Is Modus Tollens valid? | Yes. |

Is Modus Tollens useful to science? | Yes; science works by using modus tollens to prove theories false. |

Modus Ponens | If P, then Q. P is true, therefore Q is true. |

Is Modus Ponens valid? | Yes. |

Is Modus Ponens useful to science? | No; it assumes the theory is true, which we don't know. |