This is the second of Gichin Funakshi's 20 principles of Karate. This has often been interpreted as meaning that while Karate is primarily a form of self-defense (not offense), the true Karate practitioner will be so aware and so fast that as soon as they detect an attack, they strike with such swiftness and certainty that while both combatants move together, the Karate-ka strikes the winning blow. I think this is at least a little shallow, and considering Funakoshi was a Confuscian scholar and deeply contemplative individual, I'd like to think he intended a deeper reading of it too. So here's my interpretation...
There is no first strike in Karate
What this means to me is that Karate is about relationship. When I sit in a place of judgement I can say “you started it, it's your fault!” or “I struck first, I won.” But if I see everything as a form of interconnected relationship then there is no blame and no winner: somehow 'we' create the moment where conflict or achievement occurs. Karate should be first and foremost an awareness discipline. The teaching of 'self defense techniques' is, I believe, misleading. There is the whole issue of what a fight really looks like (which is frankly very ugly) as compared with what is often taught (which is choreographed). I have often seen people (including myself at times) walk out of a dojo with a greatly inflated sense of skill when dealing with 'real fighting.' This is dangerous because this attitude will tend to make you more, not less likely to get into a fight. It is important to gain a sense of physical self confidence, and some studies have been done that seem to suggest that career criminals instinctively steer clear of people who are grounded and centred regardless of their size or sex (these are cited in George Leonard's book 'The Way of Aikido'). So learning to be grounded and centred, to have sufficient physical awareness and confidence that your physicality does not say “victim” is an important learning and may prevent trouble in the first place. The attitude that goes with “I can take care of myself” tends more towards some arrogance or even mild aggression – which is more likely to attract the attention of a certain kind of trouble-maker. In these examples the 'first strike' has gone from being a physical act to an attitudinal stance. Without necessaily being aware of it, in thinking 'I can take care of myself' I walk around projecting subtle 'what are you looking at?!' vibes. I have been very fortunate to train with wise and subtle teachers (both physically and through reading some excellent books) who have encouraged me towards a deep kind of physical awareness rather than focusing on the fight. I believe it is this kind of physical awareness which should be at the heart of what we learn in Karate (or any martial art for that matter), and is also at the heart of what I consider to be 'self defence.' Even once someone seems to have engaged with us aggressively (which most commonly begins verbally), how we respond to that mentally, emotionally, and physically, can have a huge impact on whether the situation escalates. In this way, there is no point we can call the 'first strike' because every situation is an environment where many subtle forces are interacting moment to moment. This interaction begins at the subconscious level so the more aware we can be of what is going on in ourselves, in the world around us and the interface between the two, the better we can become at ensuring a first strike never becomes necessary (whether that 'strike' as an act of aggression is physical, mental or emotional).
The Kanji (Japanese writing) for Budo which means 'warrior way' is made up of 2 other Kanji: one which means 'halberds', the other means 'to stop.' So the root of the warrior path is to stop combat happening. This gives us a different idea of what it means to be a warrior than most of the popular films portray for us, and it is from this perspective that I interpret Gichin Funakoshi's second principle. With this at the heart of our understanding of the warrior way, we become warriors of compassion, warriors of peace.