It's more of an assumption than a case or argument.
assumption |əˈsʌm(p)ʃ(ə)n|
noun
a thing that is accepted as true or as certain to happen, without proof
^ Your interpretation
observation |ɒbzəˈveɪʃ(ə)n|
noun
the ability to notice things, especially significant details
hypothesis |hʌɪˈpɒθɪsɪs|
noun (pl. hypotheses |hʌɪˈpɒθɪsiːz| )
a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation
reasoning |ˈriːz(ə)nɪŋ|
noun [ mass noun ]
the action of thinking about something in a logical, sensible way
argument |ˈɑːɡjʊm(ə)nt|
noun
a reason or set of reasons given in support of an idea, action or theory
^ What I did