[pat_shaughnessy]

Great read - thanks! I love the river metaphors. The metaphysics discussion also brought back memories of college philosophy classes on Plato's theories around ideas vs. forms. Probably my memory is failing me here and someone more versed in philosophy could help me out here :) But to me it's interesting how classical philosophy could even remotely be related to computer programming.

[telemachos]

The river metaphor probably made you think of Plato. The famous quote "You can never step into the same river twice" is attributed to Heraclitus[1], but it's Plato who (first) tells us that Heraclitus said it[2].

Plato's theory of forms (or ideas - they're two ways expressing the same theory in Plato, not oppositions) is arguably a response to earlier theories of Heraclitus and Parmenides[3]. In a Heraclitean world, everything is always changing; nothing stays the same, and there is not even an underlying substance that undergoes the changing and stays itself (the way we might say there's an underlying me that was once young and is now older). In contrast to Heraclitus, Parmenides said almost the opposite (maybe - people argue a lot about what the hell Parmenides said): nothing ever changes; the only reality is being, which is always (and only) what it is and doesn't change. Heraclitus denied the reality of stability, and Parmenides denied the reality of change. Plato is trying to bridge these two theories: he wants to agree with Heraclitus that the world shows massive change, but also with Parmenides that not everything changes, and that something must subsist all the changing. Forms help to explain permanence for Plato: a form is an eternal, immutable, non-sensory X that all the concrete particular x things participate in. For example, the form of Beauty (which is permanent, unchanging and perfectly beautiful, but non-sensory - a funny combination) is what makes actual beautiful things (which can change and become ugly) beautiful. When put that way without more context, Plato's theory sounds bizarre and obviously false. But he was struggling to understand what later philosophers call "properties"[3] and "the problem of universals"[4], and it turns out that that problem is not easily solved.

[1]: http://plato.stanford.edu/entries/heraclitus/

[2]: http://plato.stanford.edu/entries/heraclitus/#Flu

[3]: http://plato.stanford.edu/entries/parmenides/

[4]: http://plato.stanford.edu/entries/properties/

[5]: http://plato.stanford.edu/entries/universals-medieval/