So far, we see that it is simple common sense to believe that the watch was made by a watchmaker.

At this point, Paley introduces an analogy:

Look around the living world. Observe all the complex and intricate adaptations. Surely, these structures are more complex than watches! And just as the watch is well suited to the job of tracking time (measuring motion), so too these organisms are even better suited to the tasks of surviving and reproducing. 

How can we best explain that these organisms are so complex and well adapted? Which explanation is more plausible?

   The Random Hypothesis (H₁)

   The Design Hypothesis (H₂)

If inferring the existence of a watchmaker is plausible in the first case, then inferring the existence of a designer of all life is plausible in the second.

And considering the degrees of complexity in living beings, we can postulate the existence of an extremely intelligent designer.