We rarely change each others minds with persuasive arguments or even with concrete evidence. Nonetheless, I like to consider myself “peak oil agnostic” and open to new arguments and theories, provided they have supporting evidence.
Like any scientific theory, peak oil can never be totally proven or disprove. If world oil production begins to decline, despite high prices, then such events will just be considered evidence supporting the theory. If world oil production then declines again the following year and declines again the next year, that's just more evidence. Nothing is ever proven. At some point, we can expect the evidence that we've past peak oil would become so overwhelming that most people would have no choice but to accept it. However, one could say the same about the overwhelming evidence supporting the theory of human evolution, and we all know how controversial that theory remains.
One the other hand, what if world oil production declines, and then rises again? If non-conventional sources take over or if new oil formation begins to replenish reserves, we must consider this evidence against the theory of peak oil. If such events occurred again and again, then enough evidence would mount to defeat the theory of peak oil and perhaps replace it with another model of oil production.
Today, there is evidence supporting peak oil, such as the bell-shaped curve of U.S. oil production in the lower 48 states. There is also evidence against peak oil, such as the continual growth of reported reserves in many nations and major oil companies.
The line between legitimate evidence and conjecture blurs when one takes the actions of other people as evidence of what is in essence a geological theory. For example, does the U.S. military presence in the middle east constitute evidence for peak oil? In such cases our actions become evidence of an a priori peak or perhaps a hidden agenda kept from public scrutiny.
A stricter constructivism would one to dismiss peak oil as simply a fictional model. Peak is reach exclusively by social consensus and our notion of geology is yet another social construct. A more pragmatic constructivism may acknowledge that peak is “false but useful.” If peak oil helps people explain the world they live in, then it doesn’t matter whether it can ever be matched to an external reality.
A more contemporary, even postmodern, epistemology might view peak oil as meme, an organism with its own agenda to grow and spread. Instead of assuming as traditional
epistemology that people carry the idea of peak oil, the peak meme will define and create new social groups. The knowledge of peak then becomes an agent shaping our collective minds with a will of its own.
How do we know when to believe in peak oil? Perhaps there is an element of faith. For the agnostics like myself, I remind you: believe half of what you see and none of what you hear.