He states that to remove the causes that provoke the development of factions you either destroy the liberty which is essential for political life (“liberty is to faction what air is to fire”), what could be unwise, or make each person in the society think in the same way and have exactly same opinions, what could be impracticable.
People are always influenced by their emotions; they have different abilities, skills and experiences what makes them have various opinions and become not equally successful (distribution of property); moreover, they always attach to diverse leaders (“The latent causes of faction are thus sown in the nature of man; and we see them everywhere brought into different degrees of activity, according to the different circumstances of civil society. A zeal for different opinions concerning religion, concerning government, and many other points, as well of speculation as of practice; an attachment to different leaders ambitiously contending for pre-eminence and power”).
That is why liberty and faction are essential for any government system that is working well.
Madison thinks that a democracy lets people be totally into their individual life and not think about public good. Also, it allows those individuals to judge their own interests which will blind them to the common good (“No man is allowed to be a judge in his own case, because his interest would certainly bias his judgment, and not improbably, corrupt his integrity. With equal, nay with greater reason, a body of men are unfit to be both judges and parties at the same time” ).
The author stays in favor of large republic, because it represents