Of course, it is possible that someone without any koan (or shikantaza) background, a four-year old even, might see through a koan in a totally fresh and invigorating way. I’ve seen in my short time working koans with students that some long-time shikantaza practitioners have been doing their shikantaza in a way that when they encounter koan, it’s like warm butter spreading on toast.
That’s not true for everyone, however. For some practitioners, the shikantaza instructions (especially when the fundamental is reified as something beyond our reach) can lead to trance and avoidance of what’s really going on in life and can leave people clueless about how to bring the zazen heart forth in daily life.
There are, of course, many possible negatives of koan practice too – like competitiveness and arrogance, for example. We humans can sure make a mess of whatever we pick up.
I see the koan masters as teaching the same point as Dogen with incredibly innovative and creative ways to help us discover and actualize the fundamental point.
As many people have noted, (my koan teachers Ford, Blacker, and Rynick for example), the two practices can be very much complementary, not “this and that” as you say. Koan and shikantaza seem to me to be two foci interacting. I have gone on and on in blog posts about this and how this view elegantly fits with the overall teaching of Dogen – imv.
Granted, you and I see things differently and have come to different (provisional, I hope) conclusions. No problem. I like differences as they provide the opportunity to learn.
I’m surprised to see that although you agree with my point of caution for Soto teachers who haven’t done koan work you plan to work through the Book of Serenity with your students. Be careful, some of them might find themselves considering koan in zazen and defiling their shikantaza! :-)
Seriously, I suggest that you don’t. From what I’ve read of your views on koan and shikantaza, I wonder if you might be misleading your community by working through koan with them – koan that you yourself have not worked through with anybody. Perhaps qualifying what your doing by saying that this is just your view….
Specifically, you seem to see koan and shikantaza as rigidly different (I say this from seeing your comments on your blog and at ZFI) and this itself suggests to me that there might be a better answer than how you would tend to interpret any koan.
If you would like to discuss this further, I suggest that we have a Skype conversation.