Toastmasters Speech Two

John Heraghty

I think, therefore I am

'I think therefore I am' - so goes the famous philosophical quotation from the renowned 17th century mathematician and philosopher Rene Descartes. I was always fascinated by the expression, and it always piqued my interest, but I never followed through on my teenage interests in philosophy, which included not taking up a CAO offer after the Leaving Cert, thus sending me down a different path completely.

But in recent times, I have reacquainted myself with the field of philosophy, if only in a 'dabbling' sort of way.

So, I would like to give a very broad, general background on the writings of Descartes, which led him to the famous phrase.

He set out in 1641 to explore what it is to be human, to try and figure out what exactly constitutes the mind, and to figure out if we can be certain that everything we see around us is exactly as it appears to be.

It was this examination of how everything appears to be that made up the majority of his huge undertaking 'Meditations on first philosophy', in which he cast doubt over the nature of reality, is there an external world independent from his own mind, and how could he be sure that anything exists, including himself!!

Chief among these doubting mechanisms, were his now famous 'arguments' from the first meditations. The three arguments were:

- The argument of error, or the appearance/reality gap

- The argument of dreaming

and

- The evil demon argument

So, the argument of error.

When we observe an object, or have an experience of the outside world by way of our senses, it is often the case that the mental picture created in our minds is not a true depiction of how the object actually is. For example, if you look at a pencil in a glass of water, the pencil appears to be bent or crooked. And you can imagine this or any other optical illusion like it.

Another example, if you eat your favourite food at a time when you are flu-ridden, it can taste decidedly unpleasant. In each of these cases, you know that there is a reason for the mismatch between the object as it is in the real world, and the mental picture that is created in your mind.

But how can you know for sure that your senses are representing the true nature of any object as it exists, if there are so many opportunities for your senses to be wrong?

The argument of dreaming.

As you can guess, this argument was simply that when we are asleep, and dreaming, we often think that we are having a 'live' experience, and it's not until you are awake that you reflect on the dream, and realise how ludicrous and surreal it was. But Descartes argued, how do we know for sure that we are not in a constant state of dreaming? He also gives the example of hallucinating, and other such states that the mind can be in.

The evil demon argument.

One of the other prominent doubting arguments, was one that I found extremely quirky, and somewhat eerie - the evil demon argument. Descartes was putting forth the idea that there is a malicious third party controlling our minds, presenting a distorted picture of the external world, and deceiving us as to the true nature of reality.

His next volume of work, the 2nd meditations, would reveal the thought process that led to the famous quotation. Descartes argued that because I am having a 'mental experience', or a thought as a result of some interaction with the outside world, I cannot know for sure that the experience represents a true depiction of the external world, but I can be sure that I am at least 'having' this mental experience, or thinking!

And in order to 'have a thought' or to 'think', I must be something, and not 'nothing', I must at least exist. Thus, I think, therefore I am!

So Descartes was saying that he cannot prove that his senses aren't deceiving him, or that he is not dreaming, or that he isn't being deceived by an evil demon. But he can be sure that he at least exists! Even if it's just as a thinking entity!!

So, to sum up, Rene Descartes' famous quotation - where did it come from, how did he arrive at that statement? His arguments put forth in the 1st meditations gave doubt as to the existence of the external world, and himself. But in his second meditations, he gave us the idea of him needing to exist, in order to have thoughts, even if they are mismatched from the external world, or if all wrong.

The question as to there being an actual external world, is discussed in Descartes Third volume of the work on the subject, the Third meditations....But that my friends, is for another day.

Thank you.