Forms of the argument from Intelligent Design have been around for a very long time but have gained renewed interest recently. Has Hume managed to show the implausibility of such views or can they be massaged to counter his criticism? Take a position in the debate and show where your opponents are wrong.
The argument for design is based on the assumption of a creator or God that designed the universe due to the supposed analogous nature of the perceived order of the world and the order found in machines and as such, something that is so ordered can only be the result of an intelligent designer. The idea that things as complex as the eye, or the flagella of different micro organisms could have developed from simple structures to the more complex ones we see today would be impossible, and that these structures were the result of some divine intelligence. However it can be argued that in order for the argument for design to be sufficiently probable, order and purpose must only be observable when resulting from design.
In Hume's Dialogues Concerning Natural Religion, Philo, who is often ascribed with the most clear representation of Hume's views, argues that we cannot make broad comparisons of the universe when we have only experience of a small part of it. Reading further through Hume puts forth a number of arguments against intelligent design.
Firstly the argument from design seems to operate under the concept that intelligence can be the only active driving cause for the way the universe functions. Many occurrences in nature don't seem to require any omniscient intelligence to occur, simply occurring in non-random ordered ways simply because they follow natural physical processes, such as the formation of crystalline structures. Intelligences would be only one of many active causes in this universe.
And even if the case were true that intelligence is the driving force behind the natural phenomena that we can observe, it does not necessarily follow that it can be linked to the origins of the entire universe. Perhaps we, here on our lonely planet, are the result of a some intelligent designer, would not the same argument hold true to the existence of our designer. If they existed in this universe, and were as complex a being as to be able to create a world and all that live upon it would they also not be required to have a designer, or to have been designed itself. And if that is the case, who designs the designers designer? Would this not then require some infinite loop of divine designers. It would be simple to say that the designer exists outside our universe and as such is not held to the same rules that govern existence here but then that leaves the question of the event of the undesigned designers existence.
Also the core analogy for intelligent design is not entirely compelling and in the Dialogues Hume doesn't believe at all that the universe resembles a machine. Machines are always clearly designed for a specific use or purpose that is not always as apparent when comparing functions in nature. Some aspects of the natural universe can require leaps of imagination in order to determine their purpose. As an example, one of the co-founders of population genetics, J. Haldane, when asked if there was "anything to be concluded about the creator from the study of creation" that He has "an inordinate fondness for beetles". This is in reference to the thousands of different species of beetles that seem to quite out number any other genus on the planet. This is also added to the fact that the universes origin is ostensibly a unique case and as such analogies are pointless. While the universe contains many unique phenomena, objects, organisms etc there is only one universe, and whilst you can draw comparisons to the many parts making up the universe separately what comparison or analogy does the universe itself draw. Anything we might contrive would be akin to comparing part a whole to the object itself. The comparison of an omnipresent being to the universe may seem to fit, it would simply be another anthropomorphic analogy much like the original comparison of a human watch maker and a divine designer. The mindless nature of the universe is more analogous however to an unthinking organism that an intelligent one.
Intelligent design assumes that because the universe is complex there is no possible way that it can exist without a designer, but complexity does not automatically assume design. Nature and life are considered ordered and as such an intelligent designer has ordered them, however as I mentioned before not all complex systems require intelligence to form. Often regarded in the scientific community as an argument from ignorance since the existence of God cannot be proven false the design argument must be true, not from any actual merits of its own but only because the possible existence of a creator cannot be satisfactorily disproved. Critics of the argument for design also suggest that a designed organism contradicts evolutionary theory, that a designed creature cannot be the result of increased fitness through natural selection. It is often argued that evolutionary theory is not only a more reasonable explanation for the complexity of life but one that has falsifiable evidence.
This also touches on the argument from poor design or the dysteleological argument. This argues against the existence of a creator god under the premise that if God is omnipotent and omniscient he would have created organisms with optimal design, however as organisms all have features that are less than optimal either God didn't create all life or God is not omnipotent and omniscient. The dysteleological argument is often used as the counter to the argument form design as if creation contains these defects it cannot be the result of a intelligent designer. The argument for poor design is coherent with the theories of evolution, which suggests that features that were evolved for certain uses which no longer become relevant are then reused for other different functions which may not be optimal but rely on the least evolutionary change. It also explains why there are some structures in nature that seem to offer no relevant benefit as inherited features, due to the nature of heredity, are unable to be completely bred out. This accounts for the suboptimal nature of some natural phenomena, as natural selection is expected to push fitness to a peak, but not necessarily the highest peak. Charles Darwin and Richard Dawkins were both proponents of the argument for poor design.
Irreducible complexity is often used as a defense for the argument for design, defined by Michael Behe, a biochemist and supporter of intelligent design, as "a single system which is composed of several well-matched interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning", using a mousetrap as an example. However this theory assumes that the parts of the system that are necessary have always been as such and could not have been added or developed over time. Evolutionary theory suggests that functions that began as only advantageous could be developed further to become necessary, and often structures or functions that were at one stage necessary can lose their genetic conservation, being bred out of the population as the selection criteria acting upon them lessens. Behe's theory has been soundly rejected by the scientific community.
The concept of a fine tuned universe is also a popular theory used in defense of the argument for design which states that the fundamental laws of our universe have been "fine tuned" in order to support life, and that only with the confluence of these specific laws is life possible. This is then further speculated upon that these laws could not come about purely by chance and that only a divine intelligence could have created this perfect petri dish, that any differences in the fundamental laws of the universe would result in changes that would make many natural phenomena unable to exist. This argument is not falsifiable, making it more metaphysics than any result of science, and even if it were to be taken as speculation the argument is still not supported well by existing evidence, it is also somewhat of a tautology in that the argument states that life is able to exist because the Universe can support its existence. The speculation that if the laws of the universe where different there would be no life is also something that is not able to be tested, who is to say that life would still not exist if electromagnetism acted differently, or if any other constant of physics was different, even to a small degree.
The argument for design is, as many theories are, flawed but many proponents for the argument want it to be accepted as a viable scientific argument and so it requires falsifiability and to satisfy to a reasonable degree the burden of proof. Unlike other theories for creation and the state of life on earth as it is now, such as evolution, intelligent designs' core tenant is that an unknowable divine being created life, which as it turns out is hard to prove. There can be plenty of theoretical arguments used to try and support the teleological position but most often they fall within the realm of metaphysics not true science. Without being able to satisfy the burden of truth and outside of blind repetition of the phrase "God did it" intelligent design will not be able to legitimately stand with other theories that do not necessarily disprove the existence of god, merely provide an idea of how, not the metaphysical why.