Very few arguments are explicitly syllogistic: it is seldom that assumptions. inferences, and conclusions are all stated together in plain view. Consequently, most arguments rely heavily on background information and assumptions (facts, history, models, biases, etc.) that are not likely to be made explicit.
If one party to a discussion about some field is lacking the necessary background information and assumptions, they are unlikely to be able to make correct arguments. They will have omitted or incorrect assumptions. No matter how explicitly syllogistic such an argument seems to be, it is fallacious if an assumption (present or omitted) is incorrect. This is why expertise and authority is considered important to an argument. Without expertise, like a stopped clock you might sometimes be right, but much of the time you will be wrong.
So what does it mean when one person professes subject expertise in an argument and the other has no such expertise? Is that an invalid argument from authority? It could mean several things. It could mean "my analysis is based on better background information, so check the other guy's more carefully". No fallacy there. It could mean "if you need a heuristic clue as to who might be right, this is a defeasible shortcut." This is an informal fallacy of logic, but a very practical heuristic method of reasoning with non-monotonic logic. (See my Distrust in logic article.) Or it could mean I am right because I am an authority", in which case it is the informal fallacy argument from authority. Perhaps it could mean other things as well. Only that third option is the argument from authority, IMHO. The other two are USEFUL, perhaps more useful than classical logic as I explain in my article.
While arguing with Skeptico, I pointed out the differences between our expertise, and a number of his supporters have accused me of the argument from authority. To logically make their case, they would need to exclude the other possibilities. But what they really are doing is applying a weak form of defeasible logic: "he has sinned (never mind that we all are sinners, and don't you dare measure how egregiously or frequently we sin.)"
Jimmy_Blue, to his credit, found an excellent set of links that provide substantial background for this debate. Background that I assumed from long experience, which Skeptico plainly lacked. Background that confirms pretty much all the points I made in my initial response to Skeptico: Response to Skeptico: Must Pay for GM Seeds? I'll add one more reference, On the adoption of genetically modified seeds in developing countries... which confirms my claims about farm productivity increases and GM seed monopoly. "...these technologies can bring about major cost savings in pest control and reduce negative environmental externalities through reductions in the use of toxic pesticides. Studies by Qaim and Zilberman (2003) and Thirtle et al. (2003) reveal that GM crops can also increase yields in situations where pesticides are underused."
Mike Huben I think makes a relevant point that does appear to be a fairly reasonable answer to Skeptico's question - that farmers must buy GM seed in order to remain competitve because of the various pressures on farmers resulting in particular from technological advances reducing commodity prices. Combine this with the possibility of monopolistic supply of GM seed, and economic pressures could result in a stark choice - buy GM seed or don't farm anymore.
The must comes from the fact that if a farmer wanted to stay a farmer, they would have to buy GM seed to remain competitive with other farmers - particularly the large corporate ones. Almost a compulsion by choice if you will.
Correct me if I am wrong in this summation.
Spot on. In my book, Jimmy_Blue is an excellent life-long student: not because he agreed with me, but because he constructively resolved a controversy with his own directed research, and shared the results. He avoided the mistake of confirmation bias (if he started with Skeptico's position), which often afflicts us skeptics just like ordinary people. I can get really pompous here and declare that was one of my motives, to goad people into learning for themselves, but it's obvious to me that Jimmy_Blue doesn't need to be taught by me. My hat's off to you!
Jimmy_Blue also spends a lot of his response fisking my style of argument, rather than the content. I can live with that. I've adopted an "afflict the comfortable" style, which I find handy for ridiculing pompous bullshitters (and Skeptico is one in this political subject. He's merely pompous in more scientific subjects.) Jimmy_Blue concludes "your argument does come across as probably valid but expressed by a total tosser" Probably valid: that's a much better judgement than I expected from any of Skeptico's supporters -- thank you Jimmy_Blue. Am I a "total tosser"? Well, since Jimmy_Blue spends his response showing how I do the same obnoxious things Skeptico does, shall I infer that he also thinks Skeptico is a "total tosser"? I can live with that: that's one of the things I set out to demonstrate.
A last couple of points about Skeptico's apparent ignorance of the subject that it would be good to clarify.
First, Skeptico and I have not been as clear (in our terminology) as we should have been about productivity of GM crops. Skeptico is correct that GM crops generally do not increase YIELD PER ACRE, which is one measure of productivity. But that measure is too narrow for this discussion, as anybody with a background in agricultural economics should know. The normal meaning of the word productivity in agricultural economics is yield divided by total costs of production, which include land, labor, and capital. GM crops have been designed to increase that latter form of productivity, and there is substantial evidence that they do (as documented in my additional reference.) That latter form of technologically-driven productivity is why farmers MUST buy GM seed or go bankrupt.
Skeptico's statement "There are no low food prices. Don’t you follow the news – they’re at record highs." is just wrong. As anybody at all familiar with agriculture knows, the prices of agricultural commodities have (long term) been declining for many decades. Jimmy_Blue's sources affirm that. Skeptico said something very stupid, based on short-term price information and his own ignorance. Unless you want to believe that he was intending to mislead us.