When I sometimes make a confident statement (for example) "All great men marry once in their life" there is always someone who refutes it. So to lighten up the situation what's some good conversation lines, phrases and expressions etc to use? Like "Yes, there is always a 'but'".
Also I am not talking about being funny here because I usually stick to my idea while giving the other guy some leeway.
So what are some tactful sentences that I could use so the other person understands that the topic is open for discussion or debate?