A fair question. I'm only about 5'8" but I'm fairly solidly constructed so have gotten the "brute force assertion" more than once. (And size does matter, no matter what they say, uhm)
But a fairly simple thing is to have a simple hands on shoulder connection, remove their connection to the ground in the subtlest way your skill allows, such that they stagger and have to take a step. You can say, "That thar is Aiki!". The same thing gets applied in locks, throws and strikes, yippee. (For the judo purists it's the subtler setup to kuzushi than more observable timing and pressure set ups)
Let's get back to the original question. I am actually only half-joking. On a more serious note, what are good "demonstrations" for someone who shows up at your dojo ?
What Budd has suggested reminds me of the first time my Sifu, Sam Chin, placed his hands on me. It didn't feel heavy, but the ground beneath my feet seem to be wobbling and everything i tried seems to be useless.
Cady Goldfield wrote:
However, his son Kisshomaru eliminated the internal elements from the modernized approach to aikido that became the Aikikai method... which was the mainstream, mass-introduced aikido sent out around the world by the young missionary teachers who were rapidly trained and promoted in that new version.
The other thing that i think we need to be realistic about is that we live in an age where martial art as a pure fighting art is fast losing relevance -- how many of us have to actually be in a real fight for survival on a daily basis ? So i think it is not a bad idea that martial arts evolve to maintain some semblance of relevance. What Kisshomaru did was one possible way of evolving the art -- perhaps not to the liking of some of us. What other ways of evolution would we like to see ?