wouldn't do such a thing
日本人ならそんなことはしないでしょう。
A Japanese person wouldn’t do such a thing, would they?
もし私があなたであるならそんなことはしないでしょう。
If I were you, I wouldn't do that.
私なら、そんなことはしないでしょう。
If it were me, I probably wouldn't do that.
紳士であれば、そんなことはしないでしょう。
A gentleman wouldn't do such a thing.