Effective Reasoning/Informal and Formal Reasoning

Reason is what makes us human human! It is our USP (unique survival process)

Naturally, the human animal is weak, slow and lacking strong jaws or sharp claws. Yet somehow our species has come to dominate the world and everything in it, short of Mother Nature herself. How did this happen?

Evolutionary PhilosophyEdit

This is a controversial topic which proposes that, like our cousins, the great apes, we were once a forest dwelling species that abandoned or was excluded from "the Garden of Eden" and had to survive by eating grass and carrion, which somehow transmuted into wheat, rice and bread along with fishing animal hunting and herding.

The key to this transformation was (allegedly) the mastery of fire and weaponry, both of which are highly dangerous to a social species such as homo sapiens. Learning to make controllable fire and reliable tools requires high levels of communication, so emotional responses developed so that language and reason emerged.

To discover more on this, try first the work of the polymath Noam Chomsky, a professor in the Department of Linguistics & Philosophy at Massachusetts Institute of Technology (MIT) USA. He is a linguist, philosopher, cognitive scientist, logician, historian, political critic, and publisher of some very controversial critiques of the modern world.

Formal reasoningEdit

Formal reasoning is concerned only with the forms of arguments. Certain forms of arguments have been identified which are valid. In other words, if the original statements (or premises) in those arguments are true, then the conclusions must necessarily be true also. Therefore, the form:

All marbles are red. All red things are bright. Therefore, all marbles are bright.

is a valid form.

The truth of the first two statements is not of interest. But, assuming that they are true, the last statement must necessarily be true.

Formal reasoning is deductive in nature. In other words, as said above, the conclusion of a valid formal argument follows necessarily from the premises. Notice that deductive reasoning produces no new information. It simply rearranges what is already known into a new statement of the same information.

Notice also that deductive or formal reasoning does not require any reference to external reality. It can be completely divorced from external reality. Therefore:

All unicorns are white. All white things are virtuous. Therefore, all unicorns are virtuous.

is a perfectly good and valid deductive argument.

Formal reasoning is addressed in other Wikibooks - Formal Logic, and Systems of Logic.

Informal ReasoningEdit

Informal reasoning includes formal reasoning but it also is concerned with all the other elements of reasoning. It addresses the probability of truth of premises and conclusions. Informal reasoning is common, every-day reasoning.


Truth seems obvious enough - we learn to tell the truth at an early age. Unfortunately, one of the features of language is it enables us to imagine future scenarios which are fanciful (which is what fiction writers do). In short it enables us to be untruthful to ourselves as well as others.

Emotionally, we react to situations. Emotions are primitive, quick and dirty survival tools - the sort of thing that makes one jump away from a flame or lash out at an attacker. We could not survive without such tactical tools.

We humans can - uniquely, and because of language - make up stories about what might happen if we did this or that, and so predict the effect of our actions. These are the long-term strategic tools that have made mankind master of the earth.

Our reports and predictions fall along a scale: they may be entirely true, partly true, false or disastrous. Reason draws us to the positive end of this scale. thoughtless blind obedience, stupidity and madness lead to errors, some of which may literally be fatal errors. Effective reasoning is our only hope of survival today and tomorrow (just as it has been for some three million years or whenever it was that our species first emerged)


Individuals who get these stories of the future approximately right (reasonable models, accurate projections), and can marshal available resources become leaders. Those who get it radically wrong are considered mad or insane. Most of us are sometimes leaders and sometimes followers - but this is a recent innovation.

For much of human history human society has been hierarchical: people were raised from infancy to believe that they belonged to an immutable social group such as 'royalty' nobility' or 'serfdom' The Hindu caste system is perhaps the most structured, but it happened (and still happens) everywhere. Director, manager or employee; pope, cardinal or priest; Officer, NCO or private soldier, and so on.

Thinking allowedEdit

The reformation, the enlightenment and above all the twentieth century wars in Europe came about through reason. Better educated people talking together, writing treatises and printing books broke the shackles of the old order.

The age of reason is accelerating through radio, television, the Internet and mobile phone technologies. It is not important that most of the material is simply entertaining, what matters is that it gives us food for thought. We can use these toys to imagine new products, services, social orders. If human imagination is reasonable, we humans should enjoy happy and fulfilled lives. If not, then crisis, recession and chaos might ensue, so that even medieval lunatic asylums might start to look like attractive places to live!