1.1.7.7 Common Sense

Version 1.3 March 2013                                         (Previous Version)

A priori, induction, deduction, falsifiability, parsimony, coherence:

How can we know these principles work?  We see them work in practice! 

As infants we unknowingly apply such guidelines to work out what we believe and how to behave. 

As we grow up we learn more about these guidelines from family, friends and teachers, and we become more conscious of some of the guidelines, we learn to apply them more systematically.

Some professionals, in academia, science, engineering, medicine and management are expected to be well trained and excel in applying reason and logic, at least in their area of expertise.

Many of us in daily life, business, journalism and politics don’t apply them enough.

If we do not follow these principles then we get into trouble.  To take each in turn:

1.     If we don’t understand the difference between á priori and what is NOT á priori, we are likely to encounter surprises when something we thought was necessarily true turns out to be false.

2.     If we don’t act as if the sun will rise tomorrow, if we don’t plan on such expected events, we lose out in life, we live less happily, without a good education, perhaps a good job, or a good partner;

3.     If we make false predictions based on limited experience, we have “black swan” events, in science, economics and our personal lives: we stuff things up, thinking we knew everything.

4.     If we use flawed logic, or behave illogically, then we make mistakes, perhaps over confidently.

5.     If can’t assess the usefulness as well as the limits of a theory that may have been falsified, then we can be paralysed by our supposed ignorance.  All action involves uncertainty.

6.     If we make things too complex (introduce complexity which doesn’t add explanatory power, or propose agents that don’t exist) then we’ll make more errors, because we’ll get overwhelmed.

7.     If our beliefs are inconsistent with each other, or with reality, or so confusing that we don’t know what we mean, then we are wasting our effort, going back and forth, or wandering aimlessly.

If a chain of reasoning leads us down a path that seems crazy or cruel, we need to review it.

·       Even without being too intellectual, we often reject a world view, philosophy or an analysis that denies our common sense notions of truth and justice.

·       This doesn’t mean that we can use our own ignorance to reject challenging conclusions.  We need to inform our common sense and update it as we learn more.  We need to allow that sometimes our common sense is wrong and based on ignorance, and follow the path of reason and logic.

As with all reasoning techniques, the use of common sense needs to be applied on a case by case basis.  There are no simple rules to tell us when our common sense overrides a detailed analysis that appears to be logical and consistent with reality.  We can only do our best.