**STOP! ***There are some terms you need to know first …*

*There are some terms you need to know first …*

**Premise: **a statement that assumes something to be true

**Conditional Premise: **a statement where “if” is a hypothesis and “then” is a conclusion

**Logic: **the relationship between ideas, intended to produce truthful conclusions

**Inductive Logic: Specific to General**

Inductive reasoning allows for the possibility that a conclusion is false, even if all of the premises are true. Instead of being valid or invalid, inductive arguments are either *strong* or *weak*, which describes how *probable* it is that the conclusion is true. Inductive reasoning is inherently uncertain. It only deals in degrees to which, given the premises, the conclusion is *credible* according to some theory of evidence.

For example:

* (Premise) 100% of biological life forms that we know of depend on liquid water to exist. * * *

** **(Strong) If we discover a new biological life form it will likely depend on liquid water to exist.

*(Premise) All the swans I have ever seen are white. * * *

*(Weak) All swans are probably white. *

**Generalization: **proceed from a premise about a sample to a conclusion about a population

*(Premise) The majority of college students at McDaniel College don’t get enough sleep.*

*(Conclusion) Therefore, the majority of all college students probably don’t get enough sleep.*

**Prediction: **draws a conclusion about a future individual from a past sample

*(Premise) Most cats panic when placed in a moving vehicle.* * *

*(Conclusion) My cat will probably hate riding in the car too*

**Argument from Analogy: **noting the shared properties of two or more things, and from this premise inferring that they also share some further property

*(Premise) Humans can move about, solve mathematical equations, win chess games, and feel pain. *

*(Premise) Androids can also move about, solve math equations, and win chess games. * * *

*(Conclusion) Thus, itʼs probable that Androids, too, can feel pain.* * *

**Deductive Logic: General to Specific**

In deductive reasoning, if something is true of a class, or group, of things in general, it is also true for all members of that class. For example:

*(Premise) All human beings will, one day, die. * * *

*(Premise) Anastasia is a human being.*

*(Logical Truth) → Anastasia will die. * * *

Assuming that both of the first statements are true, the final statement must also be true. This type of reasoning is only *sound*, however, if the generalization premise is true. Otherwise, a statement can be “logical” according to deduction and still be untrue. For example:

*(Faulty Premise) All grandfathers are bald men. * * *

*(Premise) Harold is a bald man. * * *

*(Logical Untruth) ↛ **Harold is a grandfather.* * *

**Law of Detachment:**

The law of detachment takes two premises, a conditional premise and a premise about a member of a class. Based on the truth of both premises, a conclusion can be deduced.

*(Conditional Premise) If an angle is between 90° and 180°, then it is an obtuse angle. *

*(Premise about a Member of a Class) Angle A is 120°. *

*(Logical Truth) → Angle A is an obtuse angle. * * *

**Law of Syllogism:**

The law of syllogism takes two conditional premises and forms a conclusion by combining the hypothetical *(if)* aspect of one statement with the conclusion *(then)* of another.

*(Conditional Premise) If Larry is sick, then he will be absent. *

*(Conditional Premise) If Larry is absent, he will miss his classwork. *

*(Logical Truth) → Therefore, if Larry is sick, he will miss his classwork.* * *

**Law of Contrapositive:**

The law of contrapositive states that, in a conditional premise, if the conclusion is false, then the hypothesis must be false also.

*(Conditional Premise) If it is raining, then there are clouds in the sky. *

*(Premise Proving the Prior Conclusion False) There are no clouds in the sky. * * *

* (Logical Truth) → Thus, it is not raining. * * *

Kayla | 2016

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