How We Think; Common Ground for Thinking and Logic

People can understand and communicate with each other even if they are separated by both time and space.  When we read, for example, the lecture notes taken by a disciple of Epictetus, a Stoic philosopher who lived in ancient Rome, we can appreciate the 1900 year old sayings of the Master as if they were spoken yesterday.  When two people raised in completely different cultures and countries come together and find a common medium, they can immediately begin to communicate, and may understand each other’s feelings and thoughts.  We even imagine that we can communicate with extra-terrestrials if one day they come from other worlds to ours.

In fact, the feelings and thoughts of each individual are extremely specific and personal.  Everything we know about the external world is first received by our senses, transferred to our phenomenal mind and there our “external world model” is shaped. Then, how it can be possible that two completely unique minds can share a common medium, can communicate with each other and can understand others?  What are the principles and foundations that constitute a common base for this interaction?  If these principles are common for all rational beings, is this common base “a priori,” that is, something you already have at birth, or is it something gained with life experiences, through senses and observations?       

The human mind first creates concepts, then constructs propositions and then makes logical deductions.  A “concept” in logical terminology means “anything thought.”  This “thing” here can be an “object,” a “situation,” a “sense,” or even a “relation.”  It can be abstract or concrete, real or virtual.  Objects are the basic logical units. The human mind uses concepts and propositions constructed with these concepts in conformance with basic thinking principles and makes logical deductions, which facilitates communication with other minds through interaction.    

The basic principles of logic are valid for all humans no matter when or where and regardless from which society or culture they are.  The basic principles of logic do not need to be known to actualize their existence and functions; we think and reason according to these principles without consciously realizing that we follow them.  When these principles are not observed, contradictions in the flow of ideas happens, correct reasoning becomes impossible and the possibility of communication is lost.         

The majority of logicians accept that the three basic principles of thought are: 1. Identity, 2. Non-contradiction, and 3. The Excluded Middle.  Here the basic principle which provides consistency, continuity and the possibility of interacting with other minds is the Principle of Identity.  The Principle of Non-contradiction and The Principle of the Excluded Middle can be derived from the Identity Principle.  The great German mathematician and philosopher Gottfried Wilhelm Leibniz (1646-1716) added a new one to these three principles as “a grand principle of being and knowing”:  The Principle of Sufficient Reason.  Leibniz asserted that two principles are sufficient for the mind and logic:  The Non-contradiction (or identity) Principle as a combination of the first three principles and The Principle of Sufficient Reason.

Even if different views are presented when the validity of these principles are questioned, they are imperative and inalterable when mind and logic are considered.  In one of his essays, Leibniz writes; “The principles of mind are necessary for thought, as muscles and tendons are for walking.  Without them thinking is not possible, as the mind relies on these principles constantly.”  In this regard, these principles are related to the essence of humans:  Man can exist only with them.  This human characteristic differentiates him from other living creatures.