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How do we know, what we know?

Jürgen Kanz
Published by in Thinking · 25 June 2019
Tags: LogicalthinkingcriticalthinkingknowledgeTOCTheoryofConstraints
This is a very difficult question. Let us start with few quotes:

"I know one thing; that I know nothing"

"Never say I know"

"Don't get frightened by not knowing things. I have approximate answers, and possible beliefs, and different degrees of certainty about different things, but I'm not absolutely sure of anything. There are many things I don't know anything about. It doesn't frighten me."

It seems to me that we have to dive deeper in the area of knowing to gain some insights. Therefore, let us begin with a definition:

What is knowledge?
Knowledge is a justified true belief.

How do we know if a belief happens to be true or is, in fact, justified?
Renè Descartes asked: "What can I actually prove that I know?" He is also famous for his statement "Cogito Ergo Sum", translated into English: "I think, therefore I am".

I think we can take the works of Socrates and Descartes as the base for all sceptical or critical thinking approaches of today. But this kind of thinking called "Cartesian skeptisicm" creates an obstacle. The knowledge can only be derivied from tested logic alone:

Recently Yaneer Bar-Yam twittered: "People sometimes become frenetic to keep up with today's complexity. We are beyond the transition that exceeds what an individual can keep up with."[1]

This is an important remark, which describes very well the situation of today. An overload of information, new things and complex situations makes it more and more difficult to understand the world around us. We know less and less as a person and this leads to the intuition that we don't want and can't be always apply Cartesian skepticism. There is simply too much we would have to check and re-check. We have to rely on other sources of evidence to understand, decide and take action. All this increases the perceived complexity of humans.

We have to accept:
  1. "Knowledge must be less than certainty derived from logical principles alone."
  2. "What we know depends on the evidence we have for different factual assertions."
  3. "How strong that evidence needs to be depends on the reason we care about a particular piece of information."

This leads us to the "Five Key Types of Evidence".
  1. Proof
  2. Claims
  3. Experience
  4. Inference
  5. Deductive Testing

1. Proofs
Things that can be determined through mathematical or logical reasoning.

Two types: logical and mathematical
You can evaluate a proof by assessing whether its logic holds up.

2. Claims
Things we hear or read from others.
"New York is America's largest city"
"It takes seven years to digest gum."

The value of claims depends on:
Plausibility of the claim.
Expertise of the claimant.
Reliability of the claimant.

3. Experience
Things we have watched or directly encountered.
"It hurts to touch hot things."
"John ate lunch at noon."

The value of experiences depends on:
The reliability of our observations.

4. Inference
Things we assume based on other pieces of evidence.
"Object permanence"
"Creationism or Evolutionary Theory"
"John likes pizza because I saw him eating pizza"

The quality of inference depends on
The quality of the evidence that the inference is based on.
How big a leap the inference from the evidence.

5. Deductive Testing
The Scientific Method
"Acetaminophen outperforms a placebo."
"The earth goes around the sun".

The quality of scientific evidence depends on
Match between what was tested and the subject of interest.
Methodological rigor.

Why types of evidence matter?
Claims to knowledge are stronger:
When there is more evidence
When that evidence is itself stronger
You can't live life only as a Cartesian skeptic

Yuri Gagarin couldn't be absolutely certain that everything would go well

If you can't know anything for certain:

  1. Recognize the evidence behind each assertion.
  2. Believe that assertion in accordance with the evidence and transform it into your own assumption for further consideration.
  3. Apply your assumptions as effects in the "TOC-Thinking Processes", either partly or in a full analysis.
  4. Make use of the CLRs (Categories of Legitimate Reservations) to test the chains of assumptions.

[1] Yaneer Bar-Yam,, last accessed on June 26, 2019
[2] Jürgen Kanz, Emotion, Logic and Intuition,,-logic-and-intuition, last accessed on June 26, 2019

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