In Rav Shach's Laws of Gitin chapter 1 law 25 he brings Tosphot Gitin page 86. The Mishna says a divorce document with no witnesses but written by the hand of the husband is not valid. Tosphot says the reason is because of the time. Rav Shach explains that means Tosphot would be going by the present status to push the time of the divorce backwards in time. The regular reason there is time on a divorce is because he might marry the daughter of his brother and she might commit adultery and because she is his relative he would then write a divorce document and predate it before the time of the adultery to save her from teh death penalty.  So this is what Tosphot means. If the doc would be his own writing with no time on it we would think to put the time in the past and thus she would not be liable the death penalty for adultery. But to Tosphot this is only the opinion of R Meir (the signed witnesses cause the validity of the divorce), not R Elazar (that the witnesses that see cause the validity of the divorce). And the law of like R. Elazar. So the law is the writing of his own hand with no time and no witnesses is valid. [The writing of his own hand takes the place of witnesses to Tosphot.]

My question here is that even R Elazar might hold we go by the present status to push the time of the divorce back in time. I mean to say that Rav Shach is holding that R Elazar goes by prior status  and R Meir by present status. I think that this is not implicit in their argument  about which set of witnesses cause the validity of the divorce. But I can see that Rav Shach is saying the argument about the status is what cause the argument about the writing of his own hand. But even so, it is hard to see that the opinion that the signing witnesses is what causes the validity to depend on present status. 

[Sorry if I am being a bit short on details here. Just to fill in one issue that might cause confusion, let me say  that "status now" means what is the state of being now you assume goes back in time. Status from the being means going forward. So e.g. you have a married woman who commits adultery. Then shows up with a divorce doc. You do not know when it was given. If you go back the status now then you assume that what is the state now was probably the state as far back in time until the minute you know it was not the case. So At least there is a doubt that at the time of the act perhaps she was not married and therefore not liabe to the death penalty. But if you go by prior status then you assume she was married until the minute she shows up with the doc.]

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 In רב שך's Laws of גיטין chapter 1 law 25 he brings תוספות גיטין page 86. The Mishna says a גט divorce document  כתב ידו is not valid. תוספות says the reason is because of the time. רב שך explains that means תוספות would be going by the present status חזקא דהשתא to push the time of the גט backwards in time. The regular reason there is time on a divorce is because he might marry the daughter of his brother and she might commit adultery and because she is his relative he would then write a גט divorce document and predate it before the time of the adultery to save her from  death penalty.  So this is what תוספות means. If the גט would be his own writing with no time on it, we would think to put the time in the past, and thus she would not be liable the death penalty for adultery. But to תוספות this is only the opinion of ר' מאיר (the signed witnesses cause the validity of the divorce), not ר' אלעזר (that the witnesses that see cause the validity of the divorce). And the law of like ר' אלעזר. So the law is the כתב ידו with no time and no witnesses is valid. [The writing of his own hand takes the place of witnesses to תוספות. My question here is that even ר' אלעזר might hold we go by the present status to push the time of the divorce back in time. I mean to say that רב שך is holding that R Elazar goes by חזקא מעיקרא  and ר' מאיר by חזקא דהשתא. I think that this is not implicit in their argument  about which set of witnesses cause the validity of the divorce. But I can see that רב שך is saying the argument about the חזקות is what cause the argument about the כתב ידו. But even so, it is hard to see that the opinion that the עדי חתימה כרתי to depend on חזקא דהשתא. 

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בהלכות גיטין של רב שך פרק 1 הלכה 25 הוא מביא את תוספות גיטין עמוד פ''ו. המשנה אומרת כי  גט של כתב ידו אינו תקף. תוספות אומר שהסיבה היא בגלל הזמן. רב שך מסביר שפירוש התוספות הוא שהסטטוס הנוכחי חזקא דהשתא דוחף את הזמן של הגט לאחור בזמן. [הסיבה שיש זמן בגט היא מכיוון שהוא עלול להתחתן עם בת אחיו והיא עלולה לנאוף ומכיוון שהיא קרובת משפחתו הוא היה כותב מסמך גירושין אחרי זמן של הניאוף עם זמן מוקדם כדי להציל אותה מעונש מוות.] אז זה מה שתוספות אומר. אם הגט היה הכתיבה שלו ללא זמן עליו, היינו חושבים לשים את הזמן בעבר, וכך היא לא תחויב בעונש מוות על ניאוף. אך לתוספות זו רק דעתו של ר' מאיר (העדים החתומים גורמים לתוקף הגירושין), ולא ר' אלעזר (שהעדים הרואים גורמים לתוקף הגירושין). והחוק כמו ר' אלעזר. אז החוק הוא כתב ידו ללא זמן וללא עדים תקף. [כתיבת ידו שלו תופסת את מקומם של עדים לתוספות. השאלה שלי כאן היא שאפילו ר' אלעזר עשוי להחזיק שאנחנו הולכים לפי הסטטוס הנוכחי כדי לדחוף את זמן הגירושין אחורה בזמן. אני מתכוון לומר שרב שך קובע כי ר' אלעזר מחזיק  בחזקא מעיקרא ור' מאיר בחזקא דהשתא. אני חושב שזה לא משתמע בטיעון שלהם לגבי איזו קבוצת עדים גורמת לתוקף הגירושין. אבל אני יכול לראות שרב שך מכווין שהוויכוח על החזקות הוא הגורם לוויכוח על כתב היד. אך למרות זאת, קשה לראות כי הדעה  שעדי חתימה כרתי תלויה בחזקת דהשתא