Today, I will concisely define SEN NO SEN (TAI NO SEN) and SEN SEN NO SEN as taught and practiced in traditional/budo style Shotokan-Ryu.
Predict the opponents movements/mind and make a decisive attack, which impacts faster than their waza.
In this regard Sen no sen is the strategy and, for example, 出合 (Deai) is a noun of this. It depicts the moment of meeting. I.e. - In kumite as my opponent launches their attack, I often impact as they launch; that is, I catch them within the initiation of their attack.
先々の先 (Sen sen no sen)
In Japanese this is explained as basically "...controlling the opponents chance". So when the opponent is utilizing Sen no sen, you defeat them in their process, catching them with a kimewaza whilst they attack. Indeed, this can also be 出合い; however, on a secondary level.
Again, I must emphasize that these budo strategies are different from sports karate as they are based on pure bujutsu; that is, they are not to merely to 'snatch a point' but are fully concerted on achieving ichigekki hissatsu. Much of this is to do with MAAI, which requires that "...the impact will result in maximum damage". Therefore, in the basic equation of these two strategies, we see the optimization of speed; full use of mass; and the capitalization of 'collision': via the opponents offensive action(s).
This is literally 'infighting' which conforms with the distance in a real fight and self-defense in general.
In sum, I hope that this brief article has sufficiently summarized both Sen no sen (Tai no sen) and Sen sen no sen.
© André Bertel. Oita City, Japan (2022).