By saying "I'm certain"? Is that the language with which hypotheses are typically communicated in your circles?
By using the term "I'm certain," I am actually assigning a high level of probability to the possibility that my statement will be demonstrated to be true when evidence becomes available.
"In my circles," that is, in my professional life, I have actually used a hierarchical list of words which linguistic experts have demonstrated are understood to mean various levels of probability. By saying "I'm certain," I am actually saying that I have determined that there is a 90 or 95% probability that the hypothesis is true, based on the evidence and assumptions used to formulate it.