Logic and Rationality, Part 1

Its been a while since I've last posted and a lot has happened which has been food for thought. So let me start with this topic. I've been reading a lot of political polemics and debates. These people love to use the term logical or rational in almost every argument. It makes a lot of sense when you consider that many of the people engaging in polemics are lawyers and as such they love to use the term logic or rational to buttress their arguments. The sad part is that they don't know what logic really means. Usually, the term logic or rational as used in these types of argument refers to simple inferences. So the question arises what is logic and rational?

Logic is simply a method of reasoning but there are three types of logic: deduction, induction and abduction. Deduction is deriving the conclusions from the premises. Here is an example:

Premise A: All men are evil
Premise B: Plato is a man
Conclusion: Plato is evil

Its a simple syllogism of three steps. The conclusion is necessary from the premises, in other words, there is no new knowledge gained in the process. The statement itself can be perfectally valid, meaning if you don't assume the existence of anything outside of the statement. The problem occurs at the empirical level, the statement might not be true when applied to the real world. Like above, not all men are evil so the conclusion is not necessary because Plato might or might not be evil. In other words, deductive logic doesn't fully work in the real world but makes for a powerful tool in philosophical discussion and speculation.

Induction is deriving the conclusion from the most probable facts. For example:

Premise A: Where there is smoke there is fire
Example: Like in the kitchen
Counter Example: Unlike in the water
Observation: There is smoke on the hill
Conclusion: There is fire

Induction is a system of reasoning based on what is observed and what will most probably be the conclusion. The five step syllogism above comes to the conclusion based on observable and knowable situations. If there are situations where there is smoke but no fire the conclusion will not be absolute but might still be valid. In otherwords, the validity of the conclusion is not entirely based on the internal validity of the statement but with external validity found in the real world. While in deductive logic the premises must lead to the conclusion, in inductive logic the premises coupled with our intuition will most probably lead the conclusion. Inductive logic is the logic of probabilities. It is used by scientists to show the most probable conclusion.


The final system of logic is Abduction. Abduction begins with an hypothesis then works backward to find the if the hypothesis is correct. It is the method of reasoning used by scientists and researchers. For example:

Facts: If i throw something up it will come down
Hypothesis: There is an force which pulls objects towards each other

Or;

Facts: Human beings possess 98% genetic similarity to chimps
Hypothesis: Human beings over a period of time evolved away from chimps

Basically both those hypothesis are not more or less valid, from a strictly logical necessity prespective, from an idea that God does all the gravity or created us to be related to chimps. Essentially, Abduction is an attempt to develop a rationale for the facts, in fact Abduction does not possess any real logical validity. Induction is probabilities and deduction is internal structural necessity.

So what is rational? Rational has less to do with deductive logic and more to do with common sense based on the wealth of knowledge availible to us. For example, 3000 years ago it was rational to believe that lightning and thunder was rained down by Zeus or the rumbling volcano are the mighty Titans of myth trying to break out of the chains that have them bound in Tartarus. This is not the case if we apply the same explanations nowadays, we would consider such thoughts or ideas from individuals in our time and from big cities to be irrational based on ignorance. Such thoughts can be logical on the otherhand as long we set up the syllogism appropriately such as:
1. All thunder and lightning is caused by Zeus
2. there is thunder and lightning in Florida
con: The lightning and thunder in florida is caused by Zeus

The statement is logical but utterly irrational. Just something to think about next time we try and use logic and rationality in our arguments.