[A] deﬁnition can be anything we choose. But the arbitrariness of deﬁnitions doesn’t make truth arbitrary. Rather, it just means that in order to understand which proposition it is whose truth we’re being asked about, we need to know what the words mean. Once again, it is just a matter of pinning down the meaning in order to pin down the truth. [...] whenever something substantive seems to depend on a choice of deﬁnition—for example, if whether to take a contemplated action seems to depend on whether the action falls within the scope of some proposed deﬁnition of right—we should suspect that a tacit deﬁnition is being smuggled in, and a sleight-of-hand substitution of the tacit deﬁnition for the explicit one is occurring. Here’s a good diagnostic technique: deﬁne some made-up word in place of the familiar one that is being deﬁned, and see what apparent difference that substitution makes. [...] A deﬁnition is just an arbitrary association between a symbol and a concept; it has nothing to do with what is true or false about the world. [...] If concepts yielded to our attempts to equate them just by our proclaiming deﬁnitions in that manner, then deﬁnitions would be like magic spells, capable by their mere incantation of somehow rearranging the substantive facts of the world. Obviously, deﬁnitions have no such power. [We need arguments, not definitions] [e.g. ownership] A supporter of libertarian capitalism may argue that you are morally entitled to use your own property for your exclusive beneﬁt, because such entitlement is the very deﬁnition of the word own. But by that deﬁnition, you have not established that anything is your own until you have (somehow) established that you are morally entitled to use it for your exclusive beneﬁt. However, there is another deﬁnition of own that is often implicitly smuggled in—roughly, that if you have obtained an item by purchasing it, inheriting it, building it, and so forth, then you own it. Sleight-of-hand alternation between the explicit and implicit deﬁnition creates the illusion of having established that whatever you build, purchase, inherit, and so forth, you are necessarily entitled to use for your exclusive beneﬁt. [You need to argue that the latter implies the former]. - Gary L Drescher, Good and Real.