What does "deep" mean?

Question

I don't know if this is best suited for the philosophy stack exchange, but it is the only one I can think of. What does "deep" mean, as in, "He is a very deep thinker" or "Philosophy is the study of deep concepts and ideas"? I would like a philosophically informed answer.

Answer 1

Deep in the context of philosophy or more general in the context of ideas means:

profound, groundbreaking, far reaching, influential, powerful

Some examples of deep ideas, concepts and thoughts in the context of philosophy:

• Xenophanes’ exposure of the anthropomorphic image of the gods,
• Plato’s theory of forms,
• Aristotle’s four different types of cause,
• Kant’s insight about the limited validity of our concepts,
• Hume’s thoughts about causality as a matter of habituation,
• Popper’s idea of progress of knowledge by hypothesis and falsification.

Answer 2

As I see it, going deep means moving from learning of what-is to trying to understand why-it-is-so. This means going beyond skin-deep and trying to understand what happens under the hood (under-stand -- as in standing under the car). This means not limiting ourselves to direct observations, but trying to uncover the processes that drive the observable patters.

For example, for centuries we were puzzled by peculiar movements of some celestial objects. Eventually, Copernicus figured out that those movement patterns can be explained if we assume that Earth, rather than sitting motionlessly at the center of the Universe, spins around its axis and orbits the Sun between Venus and Mars. And then Newton figured out that those orbital trajectories can be explained if we assume the existence of the so-called universal gravity -- an invisible force of attraction between all material things.

Note that both heliocentric system and universal gravity were discovered in our minds as purely theoretical models. There was no way, at the time, to observe (and to prove) that the Earth actually spins (just ask Galileo). And it took us a 100 years after Newton's discovery to build a sensitive enough experiment to directly detect and measure the gravitational attraction between two arbitrary objects.

Now, the million dollar question is: What mental process allows us to look under the hood, to see in our minds things that cannot be perceived through our senses? Modern languages (and even Latin) have no word for that process -- but in Ancient Greek that word, I believe, was logos. Heraclitus had a few things to say about it (and about our relationship with it), as do the opening verses of John's Gospel.