I was enjoying a spirited discussion between a few friends of mine yesterday afternoon. Two of them were bitterly opposed philosophically, and were each trying to cajole the other into his point of view. The subject matter was politics and over a tangential issue I really didn’t have much personally invested in, so I simply nursed my drink and kept rhetorical score.
But something strange started to emerge… I noticed that they were both largely approaching the debate by citing verifiable facts and using a rather straightforward logical progression.
This wasn’t strange in itself (rare perhaps) except that they were each coming out of the exchange with different conclusions. I couldn’t help but smile. Both started out with the same information but came to vastly different conclusions, and yet were adamant that the other was wrong.
As I parted company with them and continued on my way, I thought about the conversation… of how two men can start with the same information and yet arrive at different understandings of what that information means. The answer can be found in the difference between deductive and inductive .
You see, with a deduction, the truth of the initial premise demands the truth of the conclusion. If your premises hold true, the conclusion must be true.
“lives in Rusk County, and Rusk County is in . Therefore, Matthew lives in Texas.”
You can add more premises but, provided they are true and do not contradict, the conclusion remains true and the argument remains valid.
But an inductive argument is another matter. An inductive argument leaves far more room for interpretation.
“Many Texans voted for Gov.. Matthew lives in Texas. Therefore, Matthew voted for Rick Perry.”
The inductive argument deals in probabilities and likelihoods, but doesn’t necessarily require absolute truth as its conclusion. One can play fast and loose with the facts of any given matter, and seem to establish a strong line of reasoning and, thus, an apparent airtight argument.
I’ve found that many arguments can appear like buildings, standing tall and strong and seemingly invincible… all while rotting along its premises and built upon a foundation of shifting sand.
Like the brilliant philosopher Cornelius Van Til once wrote “all facts are interpreted facts,” that what we see and believe to be true often depends on our own set of premises or how we understand the facts of a given matter. The ancients may have looked upon a night’s sky and seen holes in a great celestial sphere, through which a greater light shined from beyond. Yet we know these lights to be far less, or more, depending on your point of view.
My friends were each speaking out of a great wealth of passionate opinion, in exchanging their ideas and defending their convictions, using facts as each believed and understood them to be.
Nevertheless, as it all to common in such contention, it is a short step from clear deduction to a more speculative induction.
This is not to suggest a weakness in inductive reasoning. Quite the contrary… inductive reasoning can often be a light that shines into dark corridors like a great blazing torch. Yet, like a great blazing torch, it must be used with care, lest it prove destructive. An inductive argument is strongest when it has taken account of all the pertinent information and does not simply ignore relevant data that contradicts highly cherished premises.
If one would truly seek to persuade, one would do so with integrity and honesty. If we desire to truly communicate with one another, rather than simply restating the positions and arguments of others, we would do well take full account of all the information about a given issue, and take perspectives that are informed as well as well-formed.