I think the word "based" has become debased. Too often does one find "X is based on Y", particularly, "X is based on the principle of Y", though the misuse of the word "principle" deserves an article its own.

"based" could mean all sorts of things, which I shall illustrate by examples taken from the first few pages of Google hits for "is based on". Derivation: "Ubuntu is based on Debian"; Logical dependency: "critique of ethanol is based on flawed findings"; many things in between, and a sort of relationship I find it hard to characterise: "Newborn's face recognition is based on low spatial frequencies".

It's the "many things in between" which it's hard to deal with. For example: "Islam's horror of homosexuality is based on Koranic misinterpretation". "Modern `Commercial Law' is based on Ancient Babylonian Codes". With these two assertions, some sort of relationship is asserted between a contemporary phenomenon and a rule written down centuries ago and authoritative for some community in the Middle East. Is it that the old rule entails the new phenomenon, or that the new phenomenon somehow incorporates it in part? And if we get to the bottom of that, what do we make of facial recognition's relation to frequencies? Or "America's trade is based on protectionism", "Restorative justice is based on community involvement", "Atheism is based on faith", "Anti-Stalinism is based on Nazi Lies", "Quantitative easing is based on discredited economics"? In particular, if the thing which is the basis turns out to be false, or gets destroyed, etc, what is the implication for something which is "based" thereon?

Obviously, no sort of logical dependency is intended by the author of "trade is based on protectionism", after all trade is an activity and protectionism is a set of normative propositions. If protectionism is taken to refer to the practice of protectionist policies, then what would it mean for trade to be "based" thereon? Does it mean "benefit from in part", "necessarily require", "possess as historical antecedent"? And which of these sense of "based on" accounts for those other four examples? In the case of quantitative easing, what are we to make of it? A policy might work in practice, even if undertaken by people motivated by some incorrect theory, yet this possibility is easy to discount, as by the use of two simple words one may contrive to say, "X is logically dependent on, or historically derived from, or necessarily requires Y", which entails that any practice whose success cannot currently be explained may be discredited by a conflation of its historical or logical antecedents.