Put the meaning into your own words.

The specious argument treated two unrelated events as proof of a cause.

A student committee proposed moving its exhibition to a smaller room on the premise that less wall space would reduce preparation time. The rationale sounded practical, since the volunteers had only one afternoon to install the work. However, a claim that a smaller room must always be easier to prepare was specious: it ignored the possibility that the available space would require additional stands and a new arrangement.