If you chance to take part in a conversation with people arguing that they do not want their tax money to go into building huge science gadgets whose utility for humanity is doubtful and null to them in particular, you have better be equipped with a sound way to shut their mouth.

Of course, one way is to explain with patience the importance of basic science, the investment in the future, etcetera. You might like to insert well-learned quotes, such as "Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza" ("You were not made to live like beasts, but to follow virtue and knowledge" - Ulysses in Dante Alighieri's "Inferno"). Well, good luck with that - I bet your argument will not go very far with the kind of opposition I have in mind.

Instead, consider this fact. Italy, who is one of the contributors to CERN, and thus helped financing the construction of the Large Hadron Collider  in measure proportional to their gross internal product, is a country full of people who visit magicians, tarot readers, healers, etcetera. This is a huge phenomenon, and an economy which fully (estimated 99%) escapes taxation. In Italy every year an estimated 6B euros (about 7.5 billion dollars) is spent in these activities, according to a Eurispes 2010 investigation (sorry, the linked report is in Italian - I am sure it exists in English as well though).

6B euros is about the cost of the full LHC, or just a bit less. This means that Italy, alone, could have fully financed the LHC effortlessly if magicians and other charlatans had been stripped of that moneys, illegally earned. Or that, if those clowns had paid their taxes, Italy could have fully financed the LHC in two and a half years. (I remind you that constructing the LHC took several years).

So you can tell your anti-science friends that it is because of people like them, who prefer to believe in magic than in science and waste money in irrational activities, that some of their taxes are spent to finance science. If the LHC appears a huge investment of money, the sum spent becomes ridiculously small if you think that a country like Italy spent in its construction over a decade a sum of money that its citizens spend in four weeks for foolish beliefs (and I am not even discussing religion here ;-).