Full Idea
Our ordinary standards for deeming arguments to be sound vary greatly from context to context. Even the package tourist's syllogism ('It's Tuesday, so this is Belgium') may meet the operative standards for soundness.
Gist of Idea
Soundness in argument varies with context, and may be achieved very informally indeed
Source
Ian Rumfitt (Logical Necessity [2010], Intro)
Book Reference
'Modality', ed/tr. Hale,B/Hoffman,A [OUP 2010], p.36
A Reaction
No doubt one could spell out the preconceptions of package tourist reasoning, and arrive at the logical form of the implication which is being offered.