Virgo, What I take them saying is that the GP's are there, they know there was a certain time frame that they were built in, (80 years from Sneferu to KhafreX12 million blocks set= 413 blocks per day, during the period), and the only tools found have been copper and flint, so they must therefore have made the pyramids with these tools and manpower available. To me, this is an argument from default, that doesn't prove how they did it. In science, you have to offer more than: "it must be so, because there it is"! Don't you think? Cheers, Rick