 Bridges next observes that causal theorists typically maintain that the putative fact that all “X”s are reliably caused by Xs is mediated by underlying mechanisms of one sort or another. So, “X”s might be reliably caused by dogs in part through the mediation of a person’s visual system or auditory system. One’s visual apparatus might causally connect particular patterns of color and luminance produced by dogs to “X”s. One might put the point somewhat differently by saying that a causal theorist’s hypothetical “Xs causes ‘X’s” law is not a basic or fundamental law of nature, but an implemented law.