“The law of noncontradiction- which says that opposite ideas cannot both be true at the same time and in the same sense- is one of the fundamental laws of logic. Despite using that law and others, Michael continued to assert that the laws of logic don’t really exist.
It sounded like he was trying to say that the laws of logic are just a human convention; that we human beings simply invent these laws in our minds but they don’t really exist outside of our minds. Several atheists have held this position, including Dr. Stein.
When I asked Michael if that was his position, he said, “yes.” So I think asked him, “Before there were any human beings on earth, was the statement, ‘There are no human beings on earth,’ true?”
Following a long pause, Michael gave a meandering response. After some prompting, he reluctantly admitted that the statement “likely” would be true (yet he continued to cling to the idea that the laws of logic were mere human conventions).
Well, of course the statement would be true. And since there were no human minds to conceptualize it, the laws of logic can’t be a mere human convention. In addition, there are several other reasons to believe that the laws of logic are no human conventions- that they exist independently of human minds.
First, human beings change, but logic doesn’t change. The laws of logic provide an unchanging independent measuring stick of truth across changing time, culture, and human belief. They are true everywhere, at everytime, and for everyone. In fact, that’s why we call them laws- the laws of logic apply equally to all of us as do the laws of physics and math.
Second, if we each had nothing more than our own private conceptions of the laws of logic, how could communication be possible? In order for Michael to understand me and for me to understand Michael, we each must be accessing something unchanging that transcends us yet is common to us. Those are the unchanging, immaterial laws of logic. Those laws provide the bridge between minds. They also provide a bridge to the outside world. Without that bridge, we’d be locked inside our own skulls unable to access or make sense of the external world. We use that bridge, but we don’t invent it.
Third, all debates presuppose that an objective truth exists outside the mind of each debater. Each debater is trying to show that his claims are closer to that objective truth than his opponent. Every truth claim- whether it’s “God exists” or “God doesn’t exist”-requires unchangeable laws of logic. If the laws of logic were changeable human conventions, then any thought anyone conceived would be “true,” even contradictory thoughts. So “God exists” and “God does not exist” would both be “true” at the same time and in the same sense. How absurd.
Put another way, if the laws of logic were just inventions of the human mind, then every thought would have to be regarded as just an invention of the human mind. With no fixed laws by which we could reliably ground our thoughts, we couldn’t know anything confidently. That would include anything atheists or anyone else said.
Finally, it’s self-defeating for Michael to assert that the laws of logic are a human convention. Notice that Michael thinks his claim is true regardless of how human minds conceptualize it. In other words, his very claim relies on the laws not being human conventions- it relies on them being fixed laws independent of human minds. In fact, all truth claims rely on that.”
(Turek, Stealing from God, 31-34)