Gittin 18 - How does the time in the Get help?
The Sages established that a divorce document (Get) needs to have the date of its writing in it. As we mentioned earlier, it could be to prevent the husband covering up on the unfaithful wife, or to prevent the husband from unfairly using his wife's property .
But consider the following scenario: a man fights with his wife, goes and asks a scribe to write a Get for her, but then carries it with him for a long time, hoping that the situation will improve, and nevertheless divorces later. This is valid, but the date in the Get will be incorrect. So what does it help that the date is there? - People normally do not rush bad tidings, and one will not write a Get in advance.
But consider a standard case discussed on the first page: a messenger brings a Get from overseas . The date on it is surely way early compared to the giving of the Get! - In such cases, due to the court proceeding, it is well known when the divorce took place, and all know that the date on the Get is not correct.
The Talmud asks more questions about the date in the Get and concludes that it can be relied on in most cases, and that the exceptions can be dealt with separately.
Art: The Argument by William Henry Knight