Think so

Words indicating that you think something is true, but you are not completely sure about it.

• What words indicate that you think something is true, but you are not completely sure about it?
  think think it is possible believe bet would gamble would wager guess reckon speculate surmise suspect get the impression have the impression be under the impression get the idea feel have the feeling get the feeling
• What words indicate that you think something is true, but you have no proof of it?
  assume assumption presume suppose imagine take it for granted presumably I take it
• What do you say when you think something is true, but you are not sure?
  I think so I guess so as far as I know to the best of my knowledge as far as I'm aware