 The argument from causal essentialism (e.g., Shoemaker 1980, 1998). Some philosophers believe that the causal powers that a property confers on its instances are essential to it. Assuming that causal laws describe the causal powers associated with properties, it follows that these laws (or versions of them that are conditionalized on the existence of the relevant properties) are necessary truths. This is, in the first instance, only an argument for the necessity of causal laws, but perhaps it can be argued that all laws of nature are of this kind. Of course, even if this assumption is granted, the argument is only as strong as the premise that properties have their associated causal powers essentially. To support this view, Sydney Shoemaker (1980) has given a battery of epistemological arguments. He points out that our knowledge of the properties that an object possesses can only rest on their effects on us, and must therefore be grounded in the causal powers associated with these properties. But, he goes on to argue that, without a necessary connection between the properties and the associated causal powers, an object’s effects on us could not serve as a source of all the knowledge about an object’s properties that we take ourselves to possess.