 Another important question has to do with whether there are forms of why-explanation that are non-causal. If so, how important are these are in science and what is their structure? Hempel seems to have thought of causal explanations simply as those DN explanations that appeal to causal laws which he regarded as a proper subset of all laws. Thus on his view, causal and non-causal explanations share a common structure. Kitcher’s unificationist model was also intended to apply to both causal and non-causal explanations such as unifying argument patterns in linguistics. More recently, there has been a great upsurge of interest in whether there are non-causal forms of explanation, with some claiming they are ubiquitous in science (e.g., Lange 2017, Reutlinger &amp; Saatsi 2018). If there are such explanations, this raises the issue of what distinguishes them from causal explanations and whether there is some overarching theory that subsumes both causal and non-causal explanations. 