Science and vision are not opposites or even at odds. They need each other. I sometimes hear other startup folks say something along the lines of: 'If entrepreneurship was a science, then anyone could do it.' I'd like to point out that even science is a science, and still very few people can do it, let alone do it well.
Nowadays people talk about PayPal's founders as prescient geniuses who would inevitably change the world. It was, however, not so obvious that PayPal would taste its first major success by helping people sell Beanie Babies on eBay. But they had a vision, a hope, and the perseverance to try multiple iterations until they got it right.
There is much that public policy can do to support American entrepreneurs. Health insurance reform will make it easier for entrepreneurs to take a chance on a new business without putting their family's health at risk. Tort reform will make it easier to take prudent risks on new products in a number of sectors.
There is no greater country on Earth for entrepreneurship than America. In every category, from the high-tech world of Silicon Valley, where I live, to University R&D labs, to countless Main Street small business owners, Americans are taking risks, embracing new ideas and - most importantly - creating jobs.