Abstract

We are on Mars again – the favourite laboratory for philosophical experiments. Our host colleagues introduce us to some Martian stuff referred to as “T”, and ask us to help them to identify T on other possible worlds. Or, technically speaking, we are asked to determine the intension of “T”, i.e., what the term designates with respect to different possible worlds. Following a short series of experiments on the planet, we conclude that the intension of “T” depends upon three factors: (1) The semantic rule linked with the term, i.e., the way in which the term is designed to pick out its referent with respect to different possible worlds (e.g., as a definite description, or as a proper name, or as an actualised description etc.); (2) The properties of the referent of “T” in the actual world; and, (3) What we shall call ‘the metaphysical background of the universe’, i.e., what counts as a thing vs. what counts as a property of things (e.g., whether the universe is such that it contains material objects that merely happen to have their manifest properties, or whether the universe primarily contains manifest objects that merely happen to have their material constitution). As our experiments show, changing the values of any of these variables will result in a change in the reference of the term with respect to different possible worlds, viz., it will result in a change in the intension of the term. We then demonstrate how the three variables are interrelated, and specify how exactly they combine to produce a particular intension of a term. We conclude with a general “formula” that determines what will deserve to be called “T” relative to the different values of the above variables, i.e., we come up with a calculator of intensions. Finally, we also draw some morals about rigidity.