Argues in favour of a distinction between causal and theoretical explanation and claims that scientific realism can be defended for the former, but the latter can only defensibly be interpreted via instrumentalism. The truth of fundamental laws is typically defended by appeal to the argument from coincidence, or inference to the best explanation. However, if we analyse the way theoretical and causal explanations function in physics, we discover that the two have a very different status. As an illustration, Perrin's experiments, which sought to confirm Avogadro's number are properly viewed as inference to the most probable cause, not as inference to the best explanation.
Keywords: inference to the best explanation, inference to the most probable cause, instrumentalism, scientific realism