Let us suppose that I'm phoning someone abducted or kidnapped and the criminal who kidnapped him is aiming the gun at his head and ordering him to lead me to the trap he has set for me (in this case my ears have failed me and I was deceived and trapped)

Let's also suppose that I'm thinking that the size of the moon is as small as 50 cent coin because my eyes see it so (in this case my eyes have aslo failed me and I was deceived by the apparent size my eyes see)

In such cases when my senses [i.e., eyes, ears] fail me then how could I reach the truth?!

  • Get someone who has her 5 senses to tell you. This is the use of signs. Like language, sign language, Braille. You can also feel around for the truth, but make sure you have your medical papers with you to prove your need to feel around. – Gordon Sep 7 '17 at 1:09
  • Also, signs allow me to experience things I may never actually see or hear, feel etc. I have never been to Alaska, but I can "experience" it through signs (like language). So signs help me to extend my world beyond my immediate horizons (beyond my immediate ability to sense). – Gordon Sep 7 '17 at 2:20
  • If all your senses fail you, you'll be be far more concerned with mundane matters like how do you feed yourself, get a glass of water, cross the road when theres traffice about etc etc rather than troubling yourself with the 'truth'. – Mozibur Ullah Sep 7 '17 at 14:02
  • en.wikipedia.org/wiki/Brain_in_a_vat might be useful reading here. – barrycarter Sep 9 '17 at 2:14

Rationalism is the philosophical school of thought that the only way to reach the truth is through reason alone, since our senses (as you describe in your examples) are always fallible. Rationalism is usually contrasted with Empiricism, the position that our senses, despite being very error prone, are still the only reliable source we have.

DesCartes cogito is a famous example of rationalist thinking: He imagines that an evil demon is trying to deceive us and everything is really just an illusion, even our very existence is an illusion. He then tries to prove through reason and logic alone that this is impossible, and that even though we may doubt everything else, we can at least be certain of our own existence.

Similarly, Kant, who is halfway between being a rationalist and empiricist, tried to prove that some (but not all) truths about the world can be determined through reason alone. These types of truths he calls synthetic a priori.

See the Rationalism vs. Empiricism debate for more details.


The scientific mind is very tentative, subject to revision based on new evidence because we are never so sure about our senses.

If we know our senses are failing us, the right thing for us to do is to suspend judgement.

Take Arab spring for example. What evidence do you have that revolution will improve people's lives? The Cromwellian revolution killed a lot of people and created a dictator; American revolution created the world's largest mob rule, where envy ran riot and where nobody knew his place, and severed the connection between the new world and the locomotive of the world's civilization; the French revolution exterminated the best elements of the French people; Russian and China' communist revolution inflicted severe brain damage upon themselves. Even the sudden collapse of the Evil CCCP did not make things better; it made the Russians poorer and gave the rest of the world more nukes.

If you do not see any beneficent effects of revolution, a reasonable question that follows is this: how likely a revolution will make things worse?

The Brits averted a French style revolution in the first half 1800's - thanks to Macaulay's eloquence - things did change gradually for the better.

That all human knowledge is uncertain, inexact, and partial. To this doctrine we have not found any limitation whatever.

Russell, Bertrand. Human Knowledge Its Scope and limits. New York: Simon and Schuster, 1948. 507. Print.

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