3. Established beyond doubt or question; indisputable: What is certain is that every effect must have a cause.
5. Having or showing confidence; assured:
When someone says, "I am certain .." they are are clearly using definition 5. and especially in this context. Your insistence that they are using definition 3. is unreasonable, especially since you KNOW they came to this opinion via Occam's Razor.
3. Established beyond doubt or question; indisputable: What is certain is that every effect must have a cause.
5. Having or showing confidence; assured:
When someone says, "I am certain .." they are are clearly using definition 5. and especially in this context. Your insistence that they are using definition 3. is unreasonable, especially since you KNOW they came to this opinion via Occam's Razor.