Asteroid Deflection......

........ is a brilliant example of a public good. I make this assertion based on the following:

• its scale : it's not like street lighting or a lighthouse, which is fairly localised. Oh no, asteroid deflection applies to the whole of humanity
• its free-riding issues are worldwide
• it is non-excludable and it is non-rivalrous
• best of all, it is not provided by government nor by the market, so it shows that public goods are defined by their features and not be their provision.

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