Postman spends a great many words complaining about the degradation of public discourse in the US over the past few centuries. Unfortunately, for all his words, he himself does not make his case that television has caused this decline. He argues that the written word forces arguments to be logical and legible (but does not explain the existence of infamous texts like Mein Kampf). He argues that political discussion has fallen from a state of grace (the Lincoln-Douglas debates) to the current level of inanity because television limits the range of discussion. But he does not show why people in the mid-19th century would be willing to sit/stand for hours watching a speaker and why 21st century people would not be willing to do so via their television.
Television may or may not be the instrument of our destruction, but Postman did include one amazing quote which made reading the book worthwhile:
There can be no liberty for a community which lacks the means by which to detect lies.Postman does point out that television presents world events in contrast to local events. Were there less immediate world-wide events (floods, wars, etc.), perhaps we would be much more interested in local occurrences (with a concomitant rise in public awareness of errors and outrage against those mistakes)? As it now stands, we watch real-time events unaided by the filters of time and analysis.
After all, there are only so many hours in a lifetime. Who spends their days reading newspapers from last century?