Here’s a thought experiment for you. Look across the room, wherever you are. Think about how long it’d take you to walk to the opposite wall. Maybe 10 seconds? That’s probably roughly how you’d measure the distance, by thinking about how long it’d take you to walk. Now imagine if you got up, started walking, and reached the wall in 1 second. You didn’t walk faster, or change your stride, you took one step and found yourself at the opposite wall.

It’d be reality-breaking. It’s quite hard to imagine, too, if you’re trying to think what it’d really be like. It’s possible to imagine overestimating the time it would take to drive to Los Angeles, but overestimating the time it’d take to walk to the opposite wall is a different story altogether. Either your perception of distance, or of time, would have to have been radically off. Distance and time are very fundamental ways to experience the world, and to be wrong about them is to be wrong about the foundations of our connection to reality.

In fact, according to 18th century German philosopher Immanuel Kant, distance and time are the fundamental ways in which we experience the world. Kant said that we receive perceptions of the world outside through our senses, and it comes in as a rush of disorganized colors, lights, and sounds. Our brain, before we realize it, organizes these perceptions in terms of distance and time. So, when we look out at the world, we think there’s such a thing as distance and time, and we don’t realize it’s just the way our brain has organized our perceptions.

This is a pretty radical idea. Before now, we’ve looked at a couple different ways of reasoning, and justifications for each. We were told how to deliberately perform deduction by Aristotle, how to deliberately perform induction by Bacon, how to be a skeptic of deduction by Descartes, and how to be a total skeptic of induction by Hume. But there’s always been the assumption that we can examine our thinking. Kant tells us, however, that that’s not always the case. There is “preprocessing” of impressions that is done before we know we’ve received any impression which can’t be undone or examined. It’s like looking at tomato sauce and trying to imagine the tomatoes that went into it. It’s possible to make inferences, but impossible to really know about the processing or the original ingredients from the tomato sauce.

But Kant’s not done. First of all, he crosses out many of the philosophical problems that plagued philosophers before him. Free will, the origin of the universe, and the end of the universe only puzzle us because we’re trying to apply our intuitive understanding of distance and time to problems they don’t apply to. So Kant thinks all the time we’ve spent arguing about them has really just been time wasted. Our intuition about space and time can’t take us to the truth, any more than Aristotle’s logic could take us to the truth about gravity. The difference is that Kant tells us that our intuitions can’t even take us to a satisfying logical conclusion, which is why we can’t stop arguing about these philosophical problems.

Next, Kant takes on Hume. As we remember, Hume laid out a devastating critique of induction. Hume proved we can never assume that something causes something else, or even assume that there’s any reason to assume. To use the words of the great philosopher Bertrand Russell, Hume tells us that when a lunatic claims he is a fried egg, he must be disagreed with solely on the grounds that he is in a minority.

Kant agrees with Hume, but then asks why, if causation is so illogical, it’s still so tempting. Kant answers his own question, as philosophers tend to do. He tells us that causation is just another intuition, like space and time. The only difference is that causation is consciously applied, after we receive impressions, while space and time are unconsciously applied, while we’re receiving impressions.

Hume could examine and criticize causation because he was aware he was applying this intuition. He could act like a third person, seeing himself come to the logical conclusion that hot tea burns his tongue, or that hot tea causes burns on his tongue. He could also imagine the two events being coincidental, which is how he starts his critique of causation. But even the great David Hume can’t examine himself applying distance and time to his perceptions.

A philosophical friend of mine once criticized Kant’s philosophy by saying that Kant leaves no room for argument or discussion. At times like this, it seems somewhat true, because we can’t discuss something that Kant tells us we can’t really understand. Kant claims we’re liable to get stuck in a fruitless discussion, like all the philosophers before Kant bickering about free will.

So instead, let’s look at some of the evolutions of Kant’s ideas. First, the idea of intuitions proves to be a powerful one. While Bacon predicted the ways in which our intuitive thinking could lead us astray, Kant opens up this new idea of an intuitive toolbox, and of tools we apply unconsciously and consciously.

Freud, for instance, a countryman of Kant’s (sort of, because Kant’s country no longer exists by Freud’s time) 200 years later creates theories of unconscious and subconscious motivations. In short, ways in which we feel about the world are influenced or controlled by motivations we don’t know exist. While Freud’s exact theories don’t prove to be supported by science, his general idea is, and we now know that conditioning can lead to this sort of preprocessing. Someone who has been traumatized, for instance, will begin to react to a perceived threat that someone who hasn’t been will not. More interestingly, they will react before they are aware they have reacted. Their intuition preprocesses the perception and applies a fight-or-flight feeling to it, leaving them baffled as to why they are reacting so poorly to something so innocuous.

On the other end of the spectrum, Einstein, another sort-of countryman of Kant’s, puts a scientific basis behind Kant’s ideas that distance and time are fundamental intuitions. Einstein proves that time is dependent on speed, and that time literally goes slower when we go faster. Space and distance can be warped as well with gravity. Unfortunately, you need pretty complicated math to really understand this. As Kant warned us, our intuition isn’t enough.

In these past essays, we’ve covered a lot about how to know things, how to prove things, and the limits of knowledge and proofs. One thing we haven’t covered is, in retrospect, pretty surprising. We’ve never examined the tool that we’re using to cover these things. That is, we haven’t looked at language itself, and we’ve just relied on it to serve our needs, as we normally assume we can. But, as the saying goes, an assumption is a dangerous thing]. For the next time, let’s look at language itself, with Ludwig Wittgenstein as our trusty guide.