Transcript: When astronomers and physicists are trying to explain coincidences in nature with the anthropic principle they must be aware of a fundamental argument in the field of philosophy. It’s called the argument from design, and it was best put in this quote by Bertrand Russell. “You all know the argument from design. Everything in the world is made just so that we can manage to live in the world, and if the world were ever so little different, we could not manage to live in it. This is the argument from design.” Bertrand Russell’s comment is that there is no logical proof of any hypothesis such as the anthropic principle just by arguing that the world had to be the way it is so that we could exist in it. In complex situations in nature, there’s often a strong connection between function, design, and form. For example, why are mountains the size they are on the Earth? Simply, if they were any bigger, the pressure at the base of the mountain would melt the rock, so there is a natural limit. Why are animals the size they are on Earth and no bigger? Because if they were any bigger, they would break. Size of an animal increases roughly as the cube of the dimension, but the bone strength only increases as a cross sectional area, or the square of the dimension. So an animal that gets too big will in fact break. Thus there are often physical reasons why things are the way they are in the natural world, but we must uncover them.