The question I'd be asking is: if you were to fast forward now to the first funding round, and then look back on the project from inception to that date, what p

The question I'd be asking is: if you were to fast forward now to the first funding round, and then look back on the project from inception to that date, what percentage of the value did each of you contribute? Put another way: giving 25% to your co-founder means that you get the first half of the company for the idea/prototype, and you split the second half (the development phase) 50/50. Now, is your idea/prototype really worth as much as all of the development?