Law of Detachment
The law of detachment (also known as affirming the antecedent and Modus ponens) is the first form of deductive reasoning. A single conditional statement is made, and a hypothesis (P) is stated. The conclusion (Q) is then deduced from the statement and the hypothesis. The most basic form is listed below:
- P→Q (conditional statement)
- P (hypothesis stated)
- Q (conclusion deduced)
In deductive reasoning, we can conclude Q from P by using the law of detachment. However, if the conclusion (Q) is given instead of the hypothesis (P) then there is no valid conclusion.
The following is an example of an argument using the law of detachment in the form of an if-then statement:
- If an angle A>90°, then A is an obtuse angle.
- A=120°
- A is an obtuse angle.
Since the measurement of angle A is greater than 90°, we can deduce that A is an obtuse angle.
Read more about this topic: Deductive Reasoning
Famous quotes containing the words law and/or detachment:
“At the end of one millennium and nine centuries of Christianity, it remains an unshakable assumption of the law in all Christian countries and of the moral judgment of Christians everywhere that if a man and a woman, entering a room together, close the door behind them, the man will come out sadder and the woman wiser.”
—H.L. (Henry Lewis)
“There is no detachment where there is no pain. And there is no pain endured without hatred or lying unless detachment is present too.”
—Simone Weil (1909–1943)