The commenter's point is that the "predefined methodology" can be indistinguishable from active investing if it's sufficiently complex and frequent. It starts g

The commenter's point is that the "predefined methodology" can be indistinguishable from active investing if it's sufficiently complex and frequent. It starts getting pretty silly to call it passive. Otherwise an active investor could simply codify their entire investing methodology into an algorithm and start following it passively, then declare that they're just adhering to a very complex index. But quantitative investors are still active investors. If you take a widely accepted, reasonably broad market definition and an index to track it (such as the S&P 500 for equities), then sure, you're investing passively. The portfolio reallocation and equity inclusion happens according to rules which organically rise from the market definition itself. But you can creatively define a market for any kind of security and then an index methodology for tracking that market which may involve a complicated set of inclusion rules that are arguably just active investing. This is something Matt Levine has talked about in his column on a number of occasions - some active investors are now rebranding their funds as index funds for creative, synthetic indices. The practical distinction between beta and "smart beta" is a lot larger than the distinction between "smart beta" and alpha, regardless of philosophical underpinnings.