(I posted another version of this question about a week ago and got no replies; I'm hoping this description is clearer).
My blog uses the Quintus theme and has infinite scroll turned off. On the home page, there are two buttons labelled "Older posts": one at the top, and one at the bottom. The one at the top works fine (if you click it, it will take you to /page/2 of the blog), but the one of the bottom fails on the https version of my blog.
On the http version (http://unlikelyexplanations.com), clicking on this button will cause an animated spinning icon to display (the kind of thing that indicates that something is loading) and then append earlier posts to the same page. That's fine. On the https version (https://unlikelyexplanations.com), clicking on the bottom "Older Posts" button will cause the spinning icon to display and the button to disappear, but no additional posts will appear (i.e., after the icon stops spinning, the page looks exactly like it did before the button was clicked, except that the button is gone).
I've seen the same behavior on Firefox 20.0, Chrome 26.0.1410.65, and Safari 6.0.4. Before testing, I cleared cache and cookies on Chrome and Safari but not Firefox.
The blog I need help with is unlikelyexplanations.com.