What does it mean to be rational ? – Part II
 In Part I of the article titled “What does it mean to be rational?”, we mentioned that the core of rationality requires adherence to the following principles:
 Principle of NonContradiction
 Principle of The Excluded Middle
 Principle of Adequate Cause
 Principle of Epistemic Confirmation
 Principle of NonSelfDestruction
 Principle of Internal Consistency
 Principle of External Congruence
 In that same first part (of the article mentioned above), we had discussed the first 4 of these principles.
 In this second part of the article, we discuss the last 3 principles. These are:
 Principle of NonSelfDestruction
 Principle of Internal Consistency
 Principle of External Congruence
 What do we mean by these?
Principle of NonSelfDestruction
 Given a claim… the claim, if it is rational, can not destroy itself.
 If the claim destroys itself, then the claim is irrational.
 Irrational Example:
 Claim: This statement is False.
 Analysis: If the statement is false, that means it is true. And if it is true, that means it is false… and if it is false, that means it is true.
 Conclusion: To believe that the claim is true or to claim that it is true, is irrational.
 Irrational Example:
 Claim: There is no truth.
 Analysis: If the claim is true, then there is no truth, and the claim is false. So it destroys itself.
 Conclusion: To believe that the claim is true or to claim that it is true, is irrational.
 Irrational Example:
 Claim: There is no such thing as truth.
 Analysis: If the claim is true, then there is no such thing as truth, and the claim is false. So it destroys itself.
 Conclusion: To believe that the claim is true or to claim that it is true, is irrational.
 Irrational Example:
 Claim: There are no absolutes.
 Analysis: If the claim is true, then there are no absolutes, and yet the claim is making an absolute claim (that there are no absolutes). So if there are no absolutes, then this absolute claim can not be true… so the claim destroys itself.
 Conclusion: To believe that the claim is true or to claim that it is true, is irrational.
 Irrational Example:
 Claim: There are no absolute truths.
 Analysis: If the claim is true, then there are no absolute truths, and yet the claim is making an absolute claim (that there are no absolute truths). So if there are no absolute truths, then this absolutetruth claim can not be true… so the claim destroys itself.
 Conclusion: To believe that the claim is true or to claim that it is true, is irrational.
Principle of Internal Consistency
 Given a system of related claims (axioms and derived statements)
 If the system of claims and derived is NOT internally consistent, then it is irrational to claim that the system is true.
 Irrational Example:
 Axiom: definition of numbers 0, 1, 2, 3; definition of “+” operator, e.g., 1+1 = 2; definition of ““, “x”, “/” operators (subtraction, multiplication, division).
 Axiom: division by 0 is permitted and is equal to a finite number (e.g., 0).
 Analysis: division by 0 leads to inconsistencies in the number system. E.g., if 1/0 = 0, and 2/0 = 0, then 1 = 2… and 0/0 = 1 and 0/0 = 2 etc.
 Such a number (and operator) system is internally inconsistent (irrational).
 Solution: addition of axiomatic rule that prohibits division by 0.
Principle of External Congruence
 Given a claim, or a system of claims …
 If the system of claims is NOT consistent with (congruent with) what we observe of external reality…
 Then the claim (or system of claims) is irrational.
 Irrational Example:
 Claim: The earth is flat (e.g., an infinite flat 2dimensional plane).
 External observation: We board a plane at New York City, and fly towards the East at 500 miles per hour. After about 48 hours of flying, we find we have reached New York City again…
 Analysis: This observation is consistent with (congruent with) the hypothesis that the earth is a sphere… and is NOT consistent with (or congruent with) the hypothesis that the earth is an infinite flat 2dimensional plane.
 Based on this observation, it is irrational to claim (or to believe) that the earth is flat.
 Irrational Example:
 Claim: The earth is a flat surface on the back of a turtle that is supported by 4 elephants.
 External observation: We board a plane at New York City, and fly towards the East at 500 miles per hour. After about 48 hours of flying, we find we have reached New York City again… We see no signs of earthsized turtles or earthsized elephants.
 Analysis: This observation is consistent with (congruent with) the hypothesis that the earth is a sphere… and is NOT consistent with (or congruent with) the hypothesis that the earth is a flat surface on the back of a turtle that is supported by 4 elephants.
 Based on this observation, it is irrational to claim (or to believe) that the earth is a flat surface on the back of a turtle that is supported by 4 elephants.
Conclusion: What does it mean to be rational ? (Parts I & II)
 In conclusion, we asked the question “what does it mean to be rational?”
 And we found that … the core of rationality requires adherence to the following principles:
 Principle of NonContradiction
 Principle of The Excluded Middle
 Principle of Adequate Cause
 Principle of Epistemic Confirmation
 Principle of NonSelfDestruction
 Principle of Internal Consistency
 Principle of External Congruence
 The article above described what these principles mean, and provided rational and irrational examples to illustrate the principles.
