DAY 42 - Rationalism (How Do You Know?)

The beginning of knowledge is the discovery of something we do not understand.

Frank Herbert (1920 - 1986)

Modern medical science has permitted people to look inside your brain and measure your very thoughts. Through magnetic resonance imagining, the secrets of the mind are finally laid bare.

Or are they? Can a machine see your thoughts, or, like hot breath on a cold day, merely hint at what is there?

Here's what these machines can see...

1. Be Rational...

You've probably heard (or used) the plea 'be rational'. Usually, this phrase invites people to pause and consider - often when their arguments are overly emotional. However, for philosophers, this phrase acts as a cornerstone for one of the two largest schools of thought - rationalism.

Rationalism is based on the premise that, through reason alone, you can understand necessary and significant truths about the universe and the self. To a rationalist, experiences may help focus your mind, but these experiences don't teach you anything.

Key Rationalist Philosophers

Click on each name to find out more about these famous philosophers' lives and works.

Plato             St. Augustine           Kant               Hegel
Spinoza        Leibniz                     Chomsky       Descartes

2. Use Your Imagination...

Here's another term you've probably heard; it is used to evoke creative ideas or unique perspectives. However, for philosophers, the imagination becomes a powerful tool in the search for truth. Indeed, the concept of a thought experiment itself uses your imagination to develop and evaluate hypothetical ideas. Remember: Einstein's theories of relativity didn't come from experimentation...they came from his imagination!

Characters like Barney over there helped to stimulate your imagination when you were young.

Did you know?

Have you ever gotten a headache from listening to other people complain about their headache?

If so, you may have suffered from a mild version of a psychosomatic illness; that is, a physical aliment brought on by a mental or emotional stimulus. Psychosomatic illnesses derive from the mind, but can manifest themselves physically. In other words, the mind shapes reality.

Another scientific example is the use of a placebo. A placebo occurs when a non-medical treatment is provided; this can either be without the subject's knowledge or with the subject incorrectly believing they are receiving the actual treatment. Placebos are used to test the degree of impact medicines and treatments have on patients.

However, there is also evidence that the placebo itself is enough to cause significant changes in a patient's mental or physical state (more commonly called the Placebo Effect). Again, this shows that belief alone is enough to alter reality. Can you recall the phantom limb syndrome? When a person who loses a limb sometimes they have the sensation, feeling or belief that their absent limb is still attached - a phantom limb.

1. History of Psychosomatic Illness
2. Latest Research on the Placebo Effect

But can your imagination show you truth? Certainly, some things you imagine are not true. For example, you can imagine a unicorn, but they aren't real. Or are they?

Well, according to Plato, yes. Or at least, the Form is. You see, Plato believed that the world consisted of two separate, yet related existences: the World of Becoming (material) and the World of Being (immaterial). In the World of Being, the Form of a horse is the perfect, ideal representation of it. This was never achievable in our material world, which is why there is variety, both real and unreal. However, for Plato the true Form does exist and is, in fact, more real than our material 'reflections'.

Another, more famous, example is that of a triangle. Try drawing a triangle. How does it look? Is it perfect? What is perfect? Wouldn't perfect mean that the lines were perfectly straight and had no thickness? Is that even possible?

Plato argued that it was not. Yet, he still held that the World of Being was real, if something we could not physically access.

3. Plato's Cave

Imagine being born in a cave, unable to move, facing away from the opening. What would you see? Well, if it was daytime, you would see shadows (from people, animals, clouds, trees, etc) move across the wall you're facing.

How would this alter your reality? What would be true to you? And would it indeed be true?


In Plato's Cave, the World of Becoming and World of Being are examined using the allegory of people who grow up knowing nothing but flickering shadows on a cave wall. For these 'prisoners' the cave wall represents their only connection with reality - a reality that is less real than our own reality. After all, even at an early age you knew your shadow was not real.

Yet, these flickering images on the cave's wall make up the sum total of all their knowledge about the world. Later philosophers have examined the impact this weltanschauung had on their personality, language, development, social structures, etc. However, Plato merely used these unfortunate captives as a metaphor for the World of Becoming. The truth, then, was represented by the sunlight pouring into the cave's mouth - the World of Being. Sadly, Plato believed that most people spent all of their time trapped in their own materialistic mindsets, and so could neither know nor imagine a world different from their own... Does this worldview sound like anything contemporary? (Hint: look below).