Each segment of "Logical Reasoning With Mr. Fireman" appears at the very end of its respective episode prior to the role credits and lasts about two to three minutes. The segment begins with the narrator stating "And now, logical reasoning, with Mr. Fireman!" whiel showing the title card (as seen above). Mr. Fireman himself then appears on screen as he gives multiple "facts" to the audience. Using these facts, Mr. Fireman somehow is able to come up with a logical "conclusion". How Mr. Fireman reaches his conclusion is somewhat illogical, however, Mr. Fireman's conclusions always end up being true facts, regardless of how poor his reasoning may be. The segment ends with the narrator saying "Hmmhmm! (implying that the narrator agrees with Mr. Fireman's logic) And that's Logical Reasoning, with Mr. Fireman!", ending the segment.
All segments of "Logical Reasoning with Mr. Fireman!" are part of the Lenny Lego Canon. The explanation given for such segments fitting into the canon are the same as National Mr. Fireman Day I and II (two bonus videos that are not official episodes). It is stated that Mr. Fireman made these videos himself and, in the actual Lenny Lego universe, uploaded them for the public to see. However, it is never made clear who voices the narrator, but it is clear that it is not Mr. Fireman, as the voice is too different.
Logical Reasoning with Mr. Fireman will be updated for the new series "The Lenny Leggo Show". Because Mr. Fireman's character was renamed to "Jonah Flenderson", the segment will respectively be renamed to "Logical Reasoning with Jonah Flenderson!", serving the same role as before.