The key assumption that paley made was that complexity, purpose, and order are the result of design. This assumption weakens his argument because natural suffering and moral evil do not suggest order
There are many things in the universe that are evidence of bad design. For example, the test tube you use for breathing is also the tube that is used for consuming food, so there is an increased risk of choking or tectonic plates can be seen as design flaws since they cause earthquakes
The teleological argument insists on an intelligent designer nut for those who argue the universe is badly designed, they don't see the work of an intelligent designer
The universe shows signs of apparent design, rather than authentic design because we have also never seen a universe being built; we cannot come to the certain conclusion that it actually was designed
Hume argued that Paley's analogy is not strong enough to draw the conclusion that God exists because of the weak comparison of objects. Hume pointed out that a watch is complex, and has an obvious purpose, and is made by a mechanist. In conclusion we know that the watch has been designed. The human eye is also very complex, and has an obvious purpose and is organic. In conclusion, we cannot be certain that the human eye has been designed
Hume suggested that actually maybe the argument did work. Perhaps the evidence of order and design in the universe does in fact lead to the reasonable conclusion that it must have been designed. However, he then suggested we are not entitled to jump to the conclusion that the designer of the universe is actually God, an all-powerful, all-knowing or even good being. Hume suggested it could have been the work of a team of designers, or even an evil force, or perhaps, even, the work of an inferior, junior designer created the universe.