[lojban-beginners] "Why should I believe that?"

[DataPacRat <datapacrat@gmail.com>]

"Why should I believe that?" is a fairly simple phrase, and the
cornerstone of the scientific method and skeptical movement... and I'm
having a bit of a time figuring out the Lojban version. The most
relevant lujvo or gismu I can find dealing with belief is krici, which
is belief /without/ evidence or proof, the exact opposite of the sort
of belief I want to deal with. Another way to say the same idea in
English is "What evidence supports that [assertion]?", but I'm having
trouble figuring out the different lujvo; would

ma xu'acmu fi ta

translate to something like "What evidence is the basis for asserting that?"

Or should I be trying to figure out "velji'i datni" or "sidydatni"
mentioned in the entry for datni?


Thank you for your time,
-- 
DataPacRat
li te'o te'a vei pai pi'i ka'o ve'o su'i pa du li no .i je'a melbi!