BANGKOK — Thailand's political and social fabric is fraying. Indeed, the country's future looks as shaky as it has never been.

In other prosperous democracies, the middle class provides the glue that holds society together. In Thailand, by contrast, the bourgeoisie, centered in Bangkok, is barely emerging as a social and political force.

Instead, for a half-century, an unspoken social contract among four broad groups has held Thailand together: the "Palace" — a euphemism used here to avoid violating Draconian lese majeste laws; big business, the custodian of economic growth; the military, which ensures, first and foremost, the sanctity of the Palace and the moral values it represents; and the common people, mostly rural and urban poor, who accept the rule of the other three estates.