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“I think, therefore I am.” Have you heard this phrase before? In this brief clip, R.C. Sproul identifies the one reality that René Descartes could not escape through his doubt: his own existence. Today, watch the entire message for free.
This is what Descartes is getting at. He said, “Don’t just tell me what everybody else believes. Give me the argument. Show me its validity.” He said, “Even my own conjecture does not bring certitude. But I want to cut through all of the confusion of my day and get down to those basic ideas, those basic truths that are indisputable, that I can take to the bank, that I can live my life on—on the basis of certitude.” And so, from this, he set out on what I call a “systematic doubt process,” by which he, being from Missouri, that Southern part of France, he decided to question any thought or any proposition that he ever heard—to question it to death. He questioned whether the hand that he saw in front of his face was really there. He questioned his senses. He said, “How do I know that what I am perceiving in the external world really exists out there, or is not simply a hallucination in my own mind, or an illusion perpetrated by some wicked devil who’s fooling me? I can’t trust, in the final analysis, with absolute certainty, what I perceive in the external world. I’m not going to trust theological authorities. I'm not going to trust scientific authorities. I’m going to doubt everything that I can conceivably doubt.” So, Descartes embarked on this process where he doubted everything. But the one thing he couldn’t doubt was that he was doubting. Because if you doubt that you’re doubting, what are you doing? You’re doubting. So, one thing I know for sure is that I am doubting. If I doubt that I am doubting, I prove that I am doubting. Because, to doubt doubt requires doubt. So, he came to the certain conclusion that he was doubting. Then he said, “Okay, what else is clearly contained within the idea of my doubting?” Well, for someone to doubt, they must be thinking. Because doubt is a form of thinking. You can't have doubt without thought. Because doubt is an element of thought. So now he says, “If I am doubting, then I know that I am thinking. Now, if I am thinking, what else does that tell me through resistless logic,” according to Descartes? “If I am thinking—I am having thought—there must be something that is doing the thinking, because thought requires a thinker. And it’s not your thought that’s giving rise to my doubts. It’s my thought that I am immediately aware of through pure intuition, to know that I am the one who is thinking and I am doubting. And if I am thinking, and I am doubting, I must be.” So, he gives us his famous formula that we have all heard at one time or another, pronounced variously by different people, and I am going to give you this pronunciation: “Cogito Ergo Sum.” Now, perhaps the most important part of this formula is the middle word, “ergo,” which means what? It means “Therefore.” It is the word which signals a conclusion, a rational conclusion. He is saying, “Cogito”—"I think, I am cogitating”—therefore, “Sum”—“I am.” So, he finally reaches something about which he can be absolutely certain: namely, his own existence.