Explain Paley’s design argument and explain why Dawkins rejects design arguments

Paley's design argument infers intelligent design and purpose from the observable order in nature. His 1802 work Natural Theology is a comendium of supporting evidence. In its opening chapter, Paley asks us to consider stumbling upon a watch while crossing a heath. We would not suppose the watch had always been there, as we would, say, a stone, but rather we would conclude that it was the product of intelligent design: its parts are framed and put together for a purpose, and its workings too intricate to have happened into existence by mere chance. Paley uses this analogy to illustrate the conclusion of his argument, namely, that just as the manifestation of design in the watch leads us to the rational conclusion that it has a designer, so the apparant design and purpose in nature allows us to infer the existence of an intelligent designer - God. 

The teleological argument, as put forth by Paley, has been challenged by Richard Dawkins. His 1986 work, The Blind Watchmaker, attempts to establish a naturalistic explanation for the appearance of design in nature, thereby making any theological explanations redundant. Dawkins argues that the Theory of Evolution accounts for the development of life on Earth: the continual adaption of organism to their environment enabled them to survive, and accounts for the apparant 'design' and 'purpose' in nature.