按理說

按理说
ànlǐshuō
it is reasonable to say that...

CEDICT

Entry Composition

1 按理 ànlǐ according to reason; in the ordinary course of events; normally
2 說 shuō
  1. to speak; to talk; to say
  2. to explain; to comment
  3. to scold; to tell off
  4. (bound form) theory; doctrine