<p>When I read your question I first wanted to comment pointing out a possible difference in meaning between these two tags. </p>

<p>But then I looked at what questions are tagged with each of them, and I actually see no difference at all. <strong>It's a mess!</strong> Given this random usage, I agree that the tags should better be merged.</p>

<p><a href="https://stats.stackexchange.com/questions/tagged/causality" class="post-tag" title="show questions tagged &#39;causality&#39;" rel="tag">causality</a> (35) $\leftarrow$ <a href="https://stats.stackexchange.com/questions/tagged/causal-inference" class="post-tag" title="show questions tagged &#39;causal-inference&#39;" rel="tag">causal-inference</a> (225)</p>

<p>Even though the second tag has many more threads, most of them are actually about "causality" in general and not about some specific inference procedures. I have written a brief wiki excerpt for <code>[causality]</code>, so the merge is ready to go.</p>
