[For the previous post, see here.]
As I have argued, the ontological argument does not work since it assumes certain philosophical ideas and values that are not necessarily true. Here I would like to analyze the ontological argument in light of current mainstream science, and show how ineffectual it is in its interaction with the prevailing scientific worldview(s). Whatever one thinks of scientific evolutionary worldviews (both materialist and spiritual), the fact of the matter is that they are the prevailing worldviews held by most people nowadays. Discounting scientists as being "non-philosophers" is not exactly helpful if one wishes to actually interact with the mainstream scientific paradigms.
The mainstream scientific narrative is the Big Bang theory with the Neo-Darwinian evolutionary synthesis. In this metanarrative, everything began 13 GYr (billion years) ago in the Big Bang. The primordial plasma clouds began cooling down, eventually forming clouds of hydrogen gas. Lumpiness in those gas clusters resulted in the gradual compression of the nebulae to form the first stars. Some of these stars were too big and died in supernovas to generate the heavier elements (e.g. Iron, Lead, Gold, Uranium), and the first black holes too. Approximately 4.5 GYr ago, the Solar System was formed as one of these star systems, and the planets of the Solar System formed around the same time as that of the Sun. The earth cooled down, liquid water was formed and collected in puddles then lakes then seas. Somehow, a chemical reaction happened to form the first building blocks of life (DNA-first, RNA-first, with or without clay silicates), which organized itself to form the first living cell. This cell evolved over millennia to form all the living creatures on the earth today.
The mainstream evolutionary metanarrative is held by many scientists, as it is the "scientific" story taught in science textbooks around the world. In this story, change is good, because change implies ability to adapt. When the environment changes, organisms that cannot adapt die off and become extinct. Those that can survive and pass on their adaptations to their offspring. The ability to change and adapt confers selective advantage to the species, even if they may not be the alpha species in their ecosystem(s), because the environment will change. It is not "if," but "when" that would occur.
We can see here the problem this will pose for the ontological argument. If we were to use it to argue for the existence of the greatest or perfect being, those coming from the mainstream evolutionary worldviews will argue that the ability to adapt is a plus. Immutability is a minus. What is seen as being good, i.e. immutability, in the philosophers' idea of God, is perceived as being bad. What then does "greatest" mean? It must be stated here that we are evaluating the ontological argument as an apologetic argument, and therefore one should not read Christian concepts into it. Apologetically therefore, the ontological argument cannot work on those with a mainstream scientific paradigm, which covers most of the educated people. (Philosophers are the minority here, not scientists!)
Besides the concept of change, we could bring in other concepts too. What about "greatness" as defined by size and majesty? Here, the case of the dinosaurs (as understood in the mainstream scientific paradigm) is a case study in how impotent the ontological argument is. By all indications of size and the ability to inspire awe, the dinosaurs were the greatest of all known creatures. Yet, they died out about 65 MYrs ago, while the lowly reptiles and insects continued. So can they be called "great"? Should the "perfect" be defined by size and the ability to inspire awe? Yet, it is precisely the size of these creatures that cause them to become extinct at the end of the Cretaceous period. If we take one of the asteroid impact theories, the destruction of their lush habitats and the scarcity of food after the catastrophe were mostly the cause of their extinction. Therefore, the dinosaurs, for all their "greatness," weren't so great after all.
The ontological argument continues to fail miserably. While one variant is to say that God is the thing you cannot conceive of anything greater, in an evolutionary scenario, there is no one criterion for what is greatest, and therefore the whole argument doesn't make any sense either. Using this argument, there is nothing greater than the dinosaurs, but there is nothing greater than the archaebacteria either.
As I have said many times, ontology is way overrated. The ontological argument likewise is overrated, and from an apologetic viewpoint shouldn't be used.