Types of Logical Arguments

Thanks to its variety of forms, logic can serve to reach a conclusion in a wide range of situations. The three kinds of logic that can be put to task include deductive, inductive, and abductive. They are not all created equal and are arranged in order of diminishing reliability with deductive logic being sound to the point of practical surety and abductive reasoning is more of a well-considered shot in the dark.

In the case of deductive logic, the only limitation on validity is the validity of the premises, assuming the logical progression is sound. Deductive reasoning and natural deduction rely on general premises by which specific conclusions can be drawn (“Deductive and inductive logic”, n.d.). This is easily demonstrated with general premises such as the classic ‘all men are mortal’ from which the logical statement can be made, ‘Socrates is a man, therefore Socrates is mortal’.

Inductive logic works in the opposite direction, providing general statements based on specific information. This type of argument cannot be proven as true or false, only valid or invalid based on the information available and the soundness of the logical progression (More on logic”, n.d.). An example of inductive reasoning could be based on the specific data that men observed over a period of time wear jeans that are only blue, no other color, therefore all blue jeans worn by men are blue. Obviously, this is not a true conclusion, but if there is no data to refute it, it is a valid induction.

In reality, this example of inductive reasoning is really more applicable to the third type of logic, abductive reasoning. In this type, conclusions are made based on limited evidence, while inductive reasoning generally requires a more complete array of evidence. To make the jean color argument truly inductive, it would have to be all men observed over a period of time, or possibly a limited number of men over their entire lives, to limit the unknown variables. But because data is rarely so complete, abductive reasoning is a more common option. This kind of logic forms the majority of logic-based decision making in the real world (“Deductive, inductive, and abductive reasoning”, n.d.).

References

Deductive and inductive logic. (n.d.). Weber State Department of Physics. Retrieved April 28, 2013, from http://physics.weber.edu/carroll/honors/logic.htm 

Deductive, inductive and abductive Reasoning. (n.d.). Butte College. Retrieved April 28, 2013, from http://butte.edu/departments/cas/tipsheets/thinking/reasoning.html 

More on logic. (n.d.). The University of Utah. Retrieved April 28, 2013, from http://www.psych.utah.edu/gordon/Classes/Psy4905Docs/PsychHistory/Cards/Logic.html