Lowry's diagnostic image: imagine, in a crisis, a shooter who has been trained by one instructor to use the front sights of the gun to aim and by another instructor to shoot instinctively. He's going to be confused. Disorganized. He'll hesitate at exactly the moment hesitation gets him killed.
The budoka who doesn't have consistency in his art, Lowry writes, is no different.1
A claim Lowry makes precisely: it is immensely, extremely difficult to teach a budo. Very, very few people are really qualified to do it.1
We tend to take it for granted that budo is fairly easy to teach so long as one has the physical and mental stamina to stick with the training. After all, there are thousands of dojo, thousands of teachers leading classes in community centers and gym annexes. But the truth, Lowry insists, is that the Japanese martial Ways are enormously, dauntingly sophisticated. Ferociously hard to learn, harder still to teach. Most people don't get that.
The naive view goes like this: I learned the mechanics of the wrist throw last month. Had it explained. Practiced it. Now I can teach it. This sounds reasonable. But being able to produce the wrist throw, and understanding its mechanics as they relate to your body, does not mean you can reproduce it in someone else's body. That person has different proportions, different reflexes, different default postures. They may encounter problems learning the wrist throw that you didn't have. Possessing the understanding of the wrist throw on a level where you can troubleshoot these situations takes years of training, experience, and insight.
In the same sense, learning the wrist throw in a comfortable training environment with a cooperative partner is one thing. Learning the timing to employ it, the setups to make it effective, the coordination to use it in combination with other movements — these are extraordinarily difficult lessons. The reality, Lowry observes, is that most budoka who learn skills like the wrist throw easily and well have a natural talent that lets them teach themselves. They learn not because of a teacher but in spite of that teacher.1
The teacher needs to do much more than just learn how to perform the technique before he can teach it. He needs to understand the underlying principles of his particular form of budo. He needs to grasp the principles of his art so thoroughly that he can see how they are embodied in any of its techniques. And he must be able to understand the reverse — how the particular (the wrist throw, in this case) reflects the general principles of the art, how the throw is consistent with and reinforces those vital principles.
This is what Lowry names as bidirectional principle coherence: the teacher must see principle ↔ technique in both directions.
When the teacher has both capacities, they can teach the foundations of the art as a whole instead of just instructing in disparate, unconnected techniques. The student receives a coherent system rather than a tool bag. When the teacher has neither, they collect "best of" techniques from different sources and string them together without any underlying coherence. The student receives the shooter-with-contradictory-instructors training and is similarly disorganized in real application.1
The reality of any budo, Lowry argues, demands a certain perspective in order to be communicated effectively. The would-be teacher has to climb to a point where their view is sufficiently broad to show others how to get to where they are and to go beyond. Even with such a teacher, the work isn't easy. Without one? Good luck.
This is why the question of finding a good teacher dominates so much budo writing. The good teacher is not a teacher who knows more techniques than the student. The good teacher has climbed to a vantage point from which the principle-technique coherence is visible. From that vantage, they can guide the student up the same path. Without that vantage, the would-be teacher can show techniques but cannot transmit the system that generates them.
The principle-technique coherence diagnostic is well-articulated across multiple budo writings, though Lowry's bidirectional framing is unusually clear. Stevens (on Tesshu) describes similar capabilities; Ratti/Westbrook document the creator-vs-transmitter sensei distinction; Cleary's anthology repeatedly returns to the same theme.
Tension to preserve: Lowry's "very, very few" qualified teachers is a strong claim. It implies that the majority of dojo students are training under teachers who lack the bidirectional capability — and that this is invisible to most students because they have no comparison point. The diagnostic for the student: can the teacher explain why the technique works as it does, in a way that connects to the art's underlying principles? Can the teacher demonstrate the same principle operating across multiple different techniques? If not, the teacher may be transmitting form without the substrate that gives the form generative power.
Open question: Bidirectional principle coherence is rare. What developmental conditions produce it? Is it primarily produced by long study under a teacher who had it (the ryu transmission model), or can it be developed independently through deep practice and reflection? The classical ryu answer: only through transmission. The modern answer often: through extensive self-study. The classical answer may be more accurate.
Lowry and Ratti/Westbrook converge on the distinction between creator sensei and transmitter sensei. Ratti/Westbrook document creator-sensei as rare figures who developed the system; transmitter-sensei as those who can faithfully pass it down without necessarily having developed it. Lowry's bidirectional-coherence diagnostic clarifies what transmitter-sensei must have: the principle-technique coherence that lets them transmit the system, not just the techniques. Both authors agree that genuine teaching capability is rare and that most teachers fall short.
Where the authors differ is in how rare each thinks the transmitter capability actually is. Ratti/Westbrook treat creator-sensei capability as exceptional but allow that genuine transmitter-sensei are more common. Lowry treats genuine transmitter capability as nearly as exceptional as creator capability — "very, very few" qualified teachers in absolute terms. Even faithful transmission is a high bar in Lowry's account.
Read both authors and a sharper picture emerges. The popular image of "the teacher who knows how to do the techniques" is several rungs below what Lowry and Ratti/Westbrook both consider genuine teaching capability. The bottom of the chain is the techniques-only instructor (most modern dojo). Above that is the technique-and-explanation instructor (some good modern dojo). Above that is the principle-technique-bidirectional teacher (rare). Above that is the creator-sensei who developed the system (exceptional). Most students do not realize they have been training under one of the bottom two layers and assume they have been receiving the upper-layer transmission. The diagnostic Lowry provides lets the student check, but few students apply it.
The bidirectional principle coherence diagnostic operates as a general teaching-quality test applicable far beyond budo.
History — ryu transmission lineage: Ryu — Japan's Knowledge Transmission Machine. The classical ryu system was built specifically to produce teachers with bidirectional coherence — long study under the headmaster (who had the capability), followed by gradual exposure to deeper principles, followed by menkyo licensing only when the capability was developed. The handshake reveals: the bidirectional coherence Lowry diagnoses is what classical ryu structurally produced; modern dan-i systems do not reliably produce it because the testing apparatus credentials technique-knowledge rather than principle-coherence.
Cross-domain — dento-kosho cycle: Dento-Kosho. The teacher who has bidirectional coherence is in the kosho phase — they understand the system well enough to generate from within it. The teacher without it is still in the rote-transmission phase, which is fine for early-stage learning but inadequate for genuine teaching. The handshake reveals: the kosho phase IS the bidirectional-coherence phase. The two are different names for the same developmental level.
Creative-practice — writing teacher quality: The bidirectional coherence diagnostic applies directly to writing pedagogy. A teacher who can show how a specific sentence reflects the principles of effective prose AND show how those principles generate specific sentences has both directions. Most writing teachers have one direction (usually principle→technique — they can explain the principles but can't generate from them effectively) or neither. The handshake reveals: any teaching discipline can be evaluated by the bidirectional test. The diagnostic transfers cleanly.
Behavioral-mechanics — institutional teaching versus practitioner teaching: The bidirectional capability Lowry diagnoses is practitioner knowledge — built from doing the work for years and reflecting on it. Institutional credentialing rarely tests for it. The handshake produces a portable diagnostic: in any teaching credential field (teaching certificates, graduate-school admission, professional-certification renewals), the credentialed teacher has demonstrated curriculum-completion but may not have bidirectional coherence. The credential is a poor proxy for actual teaching capability.
Cross-domain — apprenticeship vs classroom as teacher-capability filter: The bidirectional-coherence diagnostic explains why apprenticeship-based fields (traditional craft guilds, surgical training, classical-music conservatory, jazz tradition) tend to produce teachers with bidirectional capability while classroom-based credential systems (most modern professional certifications, most academic disciplines) do not. Apprenticeship runs on transmission; the senior is present, reading the junior continuously, judging readiness to advance. The senior's own capability is constantly visible to the junior, who can verify principle-technique coherence over years of close observation. Classroom credentialing runs on standardized testing; the instructor's own capability is masked by the standardized rubric, and the student has no opportunity to verify whether the instructor could actually generate from principles or only describe them. The handshake produces a portable claim: fields that have abandoned apprenticeship for credentialed-classroom training have also lost the structural mechanism by which bidirectional coherence transmits. Recovering apprenticeship architecture (where possible) is the structural fix. Where not possible, augmenting credentialed training with apprenticeship-style mentorship is the partial fix that many fields are quietly attempting. The fellowship-after-board-certification in medicine, the senior-partner mentorship in law, the senior-thinker tutorial in some doctoral philosophy programs — all are attempts to reinstall the senior-present-reading-the-junior dynamic that credentialed classroom training cannot deliver.
The Sharpest Implication
If bidirectional principle coherence is the actual marker of teaching capability, and if it is rare (as Lowry insists), then the modern educational system across most professional fields is misallocating teaching authority on a massive scale. Teaching credentials measure formal training and curriculum-completion; they don't test bidirectional coherence. The result: classrooms staffed by curriculum-competent instructors who can teach individual techniques but cannot transmit the underlying systems. Students learn discrete skills without acquiring the generative substrate. They produce work that looks competent but fails when novel situations require system-level adaptation. The implication beyond budo: when choosing a teacher, mentor, or coach, ask them to explain how a specific technique reflects underlying principles AND ask them to derive multiple techniques from the principles. If they can do both, you've found something rare. Most can't do either. Some can do one. Very few can do both — and those are the practitioners worth learning from.
Generative Questions