@Derekt19 it's not really outside knowledge in my opinion. seems like the statement "tigers are mammals" is simply a definition. you know that from outside knowledge, but it is also being stipulated in this case. 

@BenYusupov one idea is that it is not certain that a tiger is a mammal. the conditions in the disney are certain, making the conclusion undeniable. the reader must assume that tigers are mammals for the premise to support the conclusion. 

Detective: Mr. Ricardo is missing his credit card. His daughter is in the living room showing her mother a haul from her day at the shopping mall. Mr. Ricardo's daughter sometimes uses his credit card on such shopping days. My hypothesis is that his daughter took his credit card and has not given it back.