Without these factors (off the top of my head) - there would be no advancement.

Harley Davidson has been quite successful at selling 1909 technology at tomorrow's prices. Okay, I'm being generous, but 1909 was the year they doubled the number of cylinders in their motors. Technically those motors are no more advanced than their first year 1903 counterparts.

Good points here. These are all the things I would have said. So let's take each advance and speculate on what would stop it. I would stifle the subject through one of the means following it, below:

Market Competition/Economic Diversity. Competition is offensive (Religious or Honor system), worldwide central religious tenet, or utopia.

Atheism/Agnosticism. Competition is offensive (Religious or honor system), or utopia.

Inventive Drive.

Innovation as a Way of Life. Innovation is bad (Religious or political).

If I missed anything, feel free to add to it.

I would say "Innovation is bad (Religious or political)", "no political divisions/decentralized self-governance" and "Competition is offensive (Religious or honor system)" all together would pretty much stifle any creativity. Thus, I believe the dictatorship model, described by iggy, would be the best. Korea under Mau would be an example of just such a government in an agnostic/pantheistic setting. Denial of individuality through absolute conformity stifles creativity like nothing else. Like the Sathar, they could learn new state-approved technologies from other cultures, but never invent.

The Human spirit, Human Nature, a Drive for competion, all drive technology.

Another race, from far off worlds might just not have these qualities.  It was Humans who built Space Fleet, perhaps to conqure the other three races, but more likely just because thier cometitive nature made them want to be ready to defend against being conqured.

Vrusks extreemly orderly sociaty while having a business nature to it might not have the same drive humans bring to business (everything is bogged down in buricratic process).  Yatzerians while war like also have a deep bloodlust and enjoy on some primal level the savagry of killing up close and personal.  Dralasites well... they might be paralized a little by the achedemic ponderance of every facet of developments and thus proceed slower.

I don't know if you are dealing with a new adventure specific race, but simply put they might not have the biological or cultural drive to speed advancement.

So... in summary... how we experience advancement might not be a shared quality with other planet's indigeonous peoples, they are not humans.

That all depends on the human. Or more accurately, the human society.

Again, referencing Harley Davidson --- they sell more motorcycles per year than any other manufacturer and do so by offering a niche market: they sell only ONE type of bike whereas the other manufacturers offer multiple types (cruisers, sport bikes, standards, dual sports, motocross, etc). They are successful at selling their antiquated designs because they aren't selling motorcycles, they're selling a lifestyle. 

"Buy American" (they're just as foreign as their foreign competitors).

"Freedom" (it's a tag line they practically patented, apparently their bikes offer a sense of freedom no other bike can. Oh, wait...it's the next step of "Buy American"...as Americans we're "free" so buy our no longer American made product.)

"Lifestyle" (the bad boy outlaw bikers we at the Motor Company once detested so much.)

The list goes on. That bar & shield logo of theirs is on everything, and I do mean EVERYTHING, up to and including feminine hygiene products (I wish I was kidding). It's a household name and you can't avoid it no matter how hard you try. If you know nothing of motorcycles you know of Harley Davidson. If you know nothing of motorcycles and just mention that you're interested in buying one, the first words out of any of your similar non-motorcycle knowledge based buddys' mouths are "Gotta get a Harley, dude!"

And the sad fact is every time the Motor Company tries to embrace technology, it flops. No matter the age demographic of interested buyers, the ones who buy into the lifestyle reject any technological advances. Upside down forks, monoshock rear suspension, 6 piston brakes...forget it. Liquid cooling, more than one intake or exhaust valve, separate con rods for the pistons (they share a common crankpin...it's one bearing with two rods on it), anything that can and will improve performance...forget it. Make it big, make it heavy, make it a slug, that's what they want. It's a miracle that they got away with fuel injection and anti-lock brakes in recent years, and an equally large feat that they discontinued their century old spirnger fork in recent years as well.

But that's what their buyers want, and they're the majority. And you'll never convince them that those overweight underpowered behemoths are inferior to anything modern, because they have bought into that lifestyle hook, line, & sinker. And that majority spirit/nature/competitive drive is NOT driving for anything resembling an advance in technology.

All due to a marketing campaign that EVERY business that actually offers something beneficial envies with a passion. Think about it: if TSR had just 1% of that kind of marketing success, even Lorraine Williams could not have ruined them...and we would be buying readily available copies of Chainmail or any other TSR product in its umpteenth printing today.

And while come human cultures foster the human spirit with freedom and competition and others retard it with oppression and collectivism... still the people always strive for what is possible.  They always wish for more or something better even if they fail to achieve it.  I stick by my statement that it is a HUMAN quality of our spirit which just might not be there in another planet's people.

Actually, I've done a study on this subject and there is indeed technological advancement with every war. It's just that it is not so opaque to modern observers. You look at history and think: spears, shields, chainmail, and think that hardly anything changed for 4,000 years, but the reality is, though subtle to our jaded eyes, that technological advancement of the time was quite pronounced to warriors in those days.

Not to go into too much detail, but the tools and their materials improved and were fine tuned and branched off into many categories. Swords did not develop into 4' steal blades for many years, true, but did you know that both the two-edged longsword and great sword originated in Rome? Or that full body platemail originated in Rome? But back then, they used iron, steal was only just discovered and very expensive. But steal underwent substantial changes and strengthening and lightening over the years until they were finally able to produce the epee. Shields underwent great advancement through the Persian and Greek eras. African tribes improved upon their shields during the tribal wars of the 1700-1800's, as well as invented several combat styles and weapons that are still in use today even by American troops.

The rule of producing a product to overcome another has always been in place. The problem is that invention did not start gaining strength until the Persians. From then on, siege engines, battering rams, armor and catapults saw regular improvement, as well as inventing new ways to cause mass destruction. All of it saw regular improvement.

When people fear the strength of an approaching army, they will always seek out new ways to advance. Sometimes it is not always physical advancement, but strategic advancement. In one way or another advancement always takes place in war. Trust me, it is law. You either advance or perish.

"Techno" means 'art and knowledge'. "Teche", or art, is the skill used. "Gnosis", or knowledge, is the understanding. Both improve in war because every available brain is applied to it in order to win. The reason it is so fast today is because there are other types of wars taking place than those causing death. Corporate marketing wars and political cold wars cause advancement. These are things we did not have before America became an independent nation. Now they drive technology like physical war never did. And once the circuit was invented, a whole new realm of possibilities opened up. If Archimedes had succeeded in promoting his computer, the technological advancement of today would have taken place in ancient Greece or even Sicily.

Take away corporations and you take away high speed advancement.

What I pointed out about the changes being more subtle also applies in the surrounding social structures. Materials and processes improved. With the introduction of siege engines came moble scaffolding. With the introduction of steel came sharper and more effective farming, butchery and smithing equipment. With padded leather came quilting. Arts and humanities improved as a result as well. Don't forget, the peasantry were the armies. So whatever they learned from the military they applied in their personal ventures.

It is simply the lack of inventive spirit that we do not see too many new devices over the ages. And with monarchies and feudal powers, the peasants saw very little of the benefits over that time. Even into the 19th century, the peasantry were still predominantly working with raw materials rather than processed ones, for instance raw iron instead of steel. But look at the nobility and those serving them and you will see the advances more readily. But you have to look at the little things, not the big picture. Looking at the big picture, yes, things remained the same for thousands of years. The widespread spirit of invention came only after the introduction of corporations and democracies. (Democracies because they promote the individual and self-determination and reduced the caste mentality.)

Actually, only Zeb's mentions a monopoly by PGC, but neither Alpha Dawn nor Knight Hawks mention such a monopoly. On the contrary, small corporations were able to rise up in PGC's presence. PGC did not have a monopoly on anything. In fact, Alpha Dawn points out that they were quite diversified. Zeb's itself says that there were half a dozen of such companies, therefore contradicting itself. The smaller corporations were simply not able to reach PGC's level of interstellar commerce. Usually, the first on the scene remains the biggest and it takes a massive internal schism to change that. So the breaking the back of PGC was not a matter of breaking a monopoly as Zeb's clams, but a breaking of marketing dominance. Alpha Dawn appears to imply that the introduction of the Sathar in the first Sathar war changed things in that matter.

That isn't to say that the Zeb's material is useless. Actually, it is very useful for historical purposes of how PGC lost some of its power, but just disregard any mention of PGC having a monopoly. Clearly they did not.

Ascent you are right! How did we get the longbow, crossbow, gunpowder - leaps forward in the medieval time period.

After WW 2 there was a great debate between the Allies as to what to do with the information the Nazis garnered from their experiments; ex: submitting hundreds of Jews to freezing water to develop clothing to resist the temperatures in the North Sea for their pilots. After much debate, the information was shared as spoils of war. We do you think we got the modern US Army helmet, the Tomahawk, the survival suit for oil rig crews, fishermen, etc. All this technology was started back then that we use now.

The question is - how long does it take take idea - invention - production - mass issue AND civilian adaptation! Many things created for war are then adapted for civilian use, ex: blood clotting field dressing, etc.

Now, if it take decades to go from invention to mass issue, there is not really a stagnation and stifling. BUT, if you are talking about....100 years, 300 years - well that may be such a slow process as to be viewed by others as stagnation and stifling.

Alpha Dawn and Knight Hawks both mention smaller competitors up against PGC. PGC was simply the first to establish Frontier-wide interstellar trade. There were other interstellar traders, just not Frontier-wide. Neither Alpha Dawn nor Knight Hawks provides a list of goods and services for PGC, and they do not indicate a clear demarcation of products. Since Kim Eastland has the misunderstanding of a monopoly, or at least failed to see that there was no monopoly, his descriptions of the megacorps is flawed as well. Streel was a direct competitor to PGC. ("This is the #2 business in the Frontier, and it aggressively seeks to outdo the PGC. The Streel Corporation does not have as many offices as the PGC, but where it does have offices, SC actively tries to eliminate competition. Its tactics are often brutal, but effective." --Knight Hawks Campaign Book)

In fact, the core worlds are likely to have stronger monopoly laws and seek to have varieties of products. It is not likely that they would tolerate just one brand that they have to pay through the nose for. Remember, too, that the corporate wars of Knight Hawks took place for a reason.

As the first established and leading mega-corp, the Pan Galacticson marketing campaign is one that every business in the Frontier has envied for two centuries. Yesterday's technology at tomorrow's prices...it's more powerful than you can imagine.