MTG: Reflecting Pool

[jack]

Reflecting Pool says "Add to your mana pool one mana of any type that a land you control could produce".

"Could" explicitly looks at the results of abilities, not the costs for them. If you have a land that says "pay blah, get one black mana", and you don't have blah, then you can't use that land, but you can use Reflecting Pool to get black.

The paradox

The immediate question people ask is, if you have two of them out, can they produce any colour of mana or no colour?

The comprehensive rules say:

106.7. Some abilities produce mana based on the type of mana another permanent or permanents “could produce.” The type of mana a permanent could produce at any time includes any type of mana that an ability of that permanent would produce if the ability were to resolve at that time, taking into account any applicable replacement effects in any possible order. Ignore whether any costs of the ability could or could not be paid. If that permanent wouldn’t produce any mana under these conditions, or no type of mana can be defined this way, there’s no type of mana it could produce.

Example: Exotic Orchard has the ability “{T}: Add to your mana pool one mana of any color that a land an opponent controls could produce.” If your opponent controls no lands, activating Exotic Orchard’s mana ability will produce no mana. The same is true if you and your opponent each control no lands other than Exotic Orchards. However, if you control a Forest and an Exotic Orchard, and your opponent controls an Exotic Orchard, then each Exotic Orchard could produce {G}.

So the official ruling is that "it produces no mana".

And that's fairly clearly what's intended from the example.

But I feel the ruling doesn't really EXPLAIN it. After all, if the ruling was "if you have two reflecting pools, they both produce red or blue", it would be equally consistent with the rules, but obviously wrong

And I'm not sure how I'd word the rules to be clearer. The intent seems to be something like, "could produce" means, "could produce by anything else, but ignore the rule you're currently interpreting to avoid infinite recursion". Which is fair enough, but I'm not sure how I'd spell it out.

Postscript

I also find it a little unfair that mana of no type is no mana, not colourless mana, but there you go :)