It is not Master Hwa's "belief" that he is sweeping Toms leg...it is his Yi or "intent" on the edge of his right leg to sweep Tom.
In a well-known book that uses prestigious academic/scientific credentials, the author states that there is sometimes a need to completely dispense with the scientific framework of Tai Chi. There is also a statement that rational thinking in so many words needs to be turned off and rely on intuition and imagination. The Tai Chi Classics are even quoted as saying "Belief or Mind move the Qi".
I have to say the correct use is that Yi or intent of mind moves the Qi for it is certainly not belief, intuition or imagination that can get the job done. One cannot say for instance my “belief” or even my “belief” in my palm allowed me to strike the opponent. However, If I say my intent to strike with the edge of my hand allowed me to strike the opponent there is undoubtedly a better outcome in the offing.
There are big problems that occur and reoccur with this type of thinking which unfortunately permeates modern day Tai Chi. Stephen Hwa Ph.D. addresses these problems in his book “Uncovering the Treasure”:
“ Modern Tai Chi teaching has been shrouded in ethereal language as if logical thinking and scientific analysis do not apply to Tai Chi. Without a rational framework, Tai Chi practice has degenerated into multitudes of forms with no relevance to the original intent of the practice. Many of them have movements that could cause problems for the practitioner rather than improve their health.”