At first glance, the author's argument that in order to increase the strength of viewers and adversiting revenues a memorandum is presented by the business manager of a television station based on the decrease of devotion from viewers to local news and weather appears to be reasonable. However, further investigation reveals that there are various aspects which have been ignored. Without considering all the evidences, the argument may not be persuasive and invulnerable.
A major loophole in the argument is that the author did not provide any evidence that how much time increased for national news nor how much time decreased for weather and local news. As there are possibility that there was a very little difference in the increase or decrease and without knowing the figures it cannot be claimed. Also, the author assumed that if there are complaints regarding something peolpe would not have interest in it which may not be true as it is possible that they were complaining as they wanted it to be improved and were keenly interested in it. So, the author did not gave any facts and statistics neither he draws a rational claim, doing so would have made the argument reasonable.
Another major flaw in the argument that the author failed to provide the evidence of the cause of complaints as there might be possibility that people wanted to see local and weather news but the channel did not cover these topic in a better way or in a way the other channel covered it. Moreover, the author did not specify that regarding to which aspects these complains were, they might be regarding the content or more advertisement which break the flow of news. What region specifically complained regarding the local and weather news as only few people had compaint regarding these two categories. Had the author provided these evidences, the argument would have been a lot more convincing.
Lastly, the author assumed that devoting time to national news would give more viewers and increase advertising revenues ignoring the other aspects such as the charges for broadcasting a news on their channel. It may be possible that they had higher charge incomparison to other news channel for late night advertisement due to which local businesses canceled their contract. If an author would have conducted a opinion poll of the public regarding the replacement of weather and local news programs with nationa news program, the argument would have been cogent.
So, there are various loophole in the argument stated by the author. Therefore, a logical and convincing conclusion cannot be drawn. Had he mentioned all the evidences stated above, a satisfying conclusion could have been drawn.