Vincent's NT Word Studies
17. Thoughts (dianohmata). Only here in New Testament. Primarily with a sense of intent, purpose.A house divided against itself falleth (oikov epi oikon piptei). Some make this an enlargement on the previous sentence - a more detailed description of the general is brought to desolation, and render house falleth upon house. So Rev., margin. It might be taken metaphorically: the divided kingdom is brought to desolation, and its families and households in their party strifes are brought to ruin. Wyc., and an house shall fall on an house. Tynd., one house shall fall upon another.
Robertson's NT Word Studies
11:17 {But he} (autos de). In contrast with them. {Knowing their thoughts} (eidws autwn ta dianoemata). From dianoew, to think through or distinguish. this substantive is common in Plato, but occurs nowhere else in the N.T. It means intent, purpose. Jesus knew that they were trying to tempt him. {And a house divided against a house falleth} (kai oikos epi oikon piptei). It is not certain that diamerisqeisa (divided) is to be repeated here as in #Mt 12:25; Mr 3:25. It may mean, {and house falls upon house}, "one tumbling house knocking down its neighbor, a graphic picture of what happens when a kingdom is divided against itself" (Bruce).