How do we know that 1+1=2?
Hendrik said that we know it from our teacher. To which my response is: Why did we believe our teacher?
Budi said that the early civilisations learned about addition in terms of objects, e.g., one ox plus one ox is equal to two oxen. It was only after the Greeks made a significant breakthrough in mathematics by separating numbers with objects that number became an independent and abstract thing. One is one, not one ox. I responded by asking why we know that one ox plus one ox is equal to two oxen. The answer he gave was that they are different. One ox is different from two oxen, but they are the same object. People created numbers to state this difference. But my response to that is: How do we know that 1 is different from 2?
Andi offered a response from Christian worldview by saying that man is created in the image of God. As the image of God, man has many similarities with God. One of the similarities is the ability to count, because the essence of numbers is already in the wisdom of God. As the image of God, man also has the ability to respond to God’s general revelation (nature). Counting is man’s response to nature. I shall comment on this in a short while.
Did people create numbers, or did they know the concept of numbers as something inherently known? I think I should have used the word ‘innate’ instead of ‘inherent’. But I guess my question was not balanced, because I intentionally used different terms: numbers and the concept of numbers. To make a balanced question, I should have asked: Did people create the concept of numbers, or did they know the concept of numbers as something innate?
As far as I can see from Andi’s comment, I think he was saying that people created numbers, but the concept of numbers is innate. (Is this what you were saying, Andi?) If I could just generalise the question: Is the ability to respond to God’s general revelation something that is innate for every human being? I would say: Yes. Not only is man capable to respond, but he is also capable to respond with reason. And if man is indeed created in the image of God, I can know that 1+1=2.
I would like to end this post with the account of man and woman wrritten in Genesis 2:23:
The man said,
“This is now bone of my bones
and flesh of my flesh;
she shall be called ‘woman,’
for she was taken out of man.”
When the first man saw the first woman, he didn’t say, “O how beautiful are you!” but his first words were, “This is now bone of my bones and flesh of my flesh.” His mathematical reasoning was awakened. She is one of his many parts, but at the same time, she is one of his one part. We see here the image of God at work, for man is created in the image of His Maker. And how could it be possible unless our God is a Triune God, united in diversity, particular in universality?