In this universe with these technologies would HUMAN infantry still be useful for the military?

Question

In my previous question about galactic empires the subject of human infantry was not the main focus so it was not discussed properly.

And so I think it needs to be covered as I'm really trying to figure out if the military of the future would still use human based infantry with this particular world in mind?:

• The scale of the world is something like Warhammer 40K without magic or insane ideologies. I just mentioned the scale because in Warhammer 40K titans are a thing and in the past there were something close to aircraft carriers. So the scale is galactic - tens of thousands of populated worlds.
• The cost of making a fighting robot that is much better than a human at war is nothing more than few hours of machine work. This is how everything gets done anyway from the simplest things to the most complicated. Humans barely supervise anything and all is done by AMI.
• There is no true artificial intelligence. Instead it is AMI (Advanced Machine Intelligence) and it is basically AI-like but not human levels yet. It is capable of making human level tactical decisions and has access to vast databases and can be deployed on computational substrate the size of a fist. A machine intelligence does not prioritize its own existence unless programmed to do so; that said, it is obviously made to save energy and the machine it is in. Its cognitive performance across the board is similar to humans. AMI units run most aspects of society.
• The social situation of the empire is that all humans are on welfare. So going to the military for money is meaningless.
• Fighting machines are 100% proven to be better than humans in every military context.
• Transporting, cost or efficiency again make using humans seem very stupid. For example, let's take the excellent orb suggestion from the most voted on answer. Now the orbs would be huge in size, say 15 meters, but they can be very easily shoved in a storage space without worrying about even air for them. And that alone saves money.
• Humans then would be officers on the level of controlling a specific theater of operations. So a small group of officers would command the military operation from the ground so to be under the protection dome of the machines which is like a several kilometer area of protection from enemy hacking or jamming...etc.
• Whatever anti technology an enemy can come up with it makes sense then to come up with a solution for instead of trying to throw people in the meat grinder.
• The expected galactic battlefield is so unpredictable that humans would need insane training and equipment to expect to survive. So assume a very high gravity world and you have to give humans expensive special armors or a world of ammonia atmosphere and you also have to worry about a single rupture in the armor while machines don't care...etc
• The cost of bioengineering people or cybernetically enhancing them and so on is still more expensive than just making war machines.
• Like I said before, space battles are the primary theatre of combat. But one concept I'm still adamant about is that humans will need fighting machines to arrive on a planetary surface to do things, whatever those things are. So while it is true that the focus of all galactic powers is on capitol ships and planet killer weapons, ground warfare still exists.
• This is in regards to the standard practice of the galactic wide defense strategy of humans. Desperate situations don't count. As we all know it is theoretical to turn every person capable of using a rifle in a country into a soldier, but that is apocalypse level thinking and not standard theory or practice.
• I love Warhammer 40K to death. But they do their own things to justify infantry, and honestly I think they work.
• Mass Effect, for example, is nothing like the huge scale of my universe, so I don't think it counts.

I can provide more information; this is all that I think is relevant now.

Personally I thought of having some people still choose to be infantry, but as either officers wanting to gain more experience or insane zealots that the military sees fit to throw away in the nearest conflict.

Knightly organizations, thrill seekers, etc. are not part of the military. As a result, they are not discussed here.

I'm providing these aspects not to limit or force an answer but because they are how the world is set up. However, I have no problem with an reasonable answer that proves that infantry is still useful or a part of my concept is conflicting or anything.

So. The main question remains: In this universe would humanity use infantry? Why or why not?

Edit. Since AlexP asked for clarification on the scale of Warhammer 40K and my world: Humans control vast parts of the universe and thousands of stars. That's the closest approximation; the actual number isn't relevant.

Answer 1

They are still relevant.

Flexibility, Threat Evaluation, Randomness, and Not Being Daleks.

As you said, there is no "true" AI in your universe, only some very specialized algorithms. Since you state that they aren't a whole lot better than what we already have, we can assume that they are rather limited in several important ways. Due to this, the Empire keeps human troops around to compensate for these shortcomings.

1. The clankers are inflexible. While kill-bots can make decisions very quickly, their decision-making algorithms are very rigid. They can't come up with original decisions, and as a result have problems adjusting to changing situations. No plan survives contact with the enemy, so they still need human officers to tell them what to do when things go wrong.

2. Related to #1, the clankers don't evaluate threats well. They try, they really do, but their algorithms are meant for killing people, not deciding whether or not those people are a threat. They're good when you need your forces to be on a hair trigger, but otherwise they're pretty much useless in this respect. Like #1, this is solved by having human NCOs.

3. Randomness. For the most part, AIs' responses are "knee-jerks;" they always always respond the same way to stimuli. Sure, there's some stuff you can do to partially avert this, but anything that completely eliminates these predictable responses will also make them Chaotic Evil. Since that isn't (quite) what the Empire wants, they instead just bring along a few squishy meatbags to handle the unpredictability.

4. They're Daleks. Well, not Daleks in the sense of "talking omnicidal dustbins from Skarro", but they have a lot of similarities. Most importantly, they have an annoying tendency to exterminate anything in their path. Unfortunately for the Empire's defense budget, there are times when "go out and shoot everything" isn't an option. For example, there are often a lot of innocent civilians around when you are fighting in urban areas. Since they don't want to be known as "those guys who kill innocent civilians for no reason", they keep some Space Marines around to deal with those situations.

   Maybe they'll be able to do without us someday. Maybe some mad genius with myopia, a bulging forehead, and a cybernetic mind will devise a weapon that can go down a hole, pick out the opposition, and force it to surrender or die - without killing that gang of your own people they've got imprisoned down there. ... In the meantime, until they build a machine to replace us, my mates can handle that job - and I might be some help too.

   - Robert Heinlein, Starship Troopers

TL;DR: The clankers are useful as cannon fodder, but they can't make decisions as well as humans. The Empire still need humans to act as special forces and NCOs.

Answer 2

Against Peer Opponents

I know that sounds counter-intuitive, but bear with me. Your Drones are God's Own Killing Machines. 100% better, per your description, at not just SOME aspects of warfare than humans, but ALL aspects. So presumably guerrilla war, low-intensity fighting, avoiding civilian/infrastructure damage, commando/special operations, the lot. Anything we currently THINK you need a human brain for, your drones do and do better. But drones are fundamentally computer programs, and ALL computer programs can be hacked if you're clever enough.

Against opponents with your level of drone tech, drones are a dangerous weapon to deploy. Sure they're as hardened against cyber attack as it is possible to be. But as the history of warfare shows us, nobody builds a thing they cannot also destroy. The race of defense vs attack has never been 100% won by defense, and hacking proves no exception. Drone army assaults against Class B or lower civilizations result in bloodless (for your squishy biological members anyway) and quick victory for Drone armies. Against Class A civilizations your drones randomly swap sides, shut down, self-destruct, walk in circles, and generally render themselves inoperable or dangerous to all sides because all Class A civilizations have multiple redundant and proactive methods to scramble drones. It's inevitable, trillions of credits and thousands of scientists are assigned to do it, and it's always easier to break something than keep it working.

Enter the Poor Bloody Infantry. Every land war begins with a drone drop of some size. Maybe large if you think the enemy is unlikely to match your firewalls, maybe small if you think it's low-probability, but still worth a shot on the off-chance your latest upgrade might be a few weeks/days/hours ahead of them. The most deeply programmed code for your drones involves you being able to self-destruct/permanently shut down your drones en-mass, and you have offensive code of your own so you're not super concerned that your drone deployment will end with your enemy simply hacking them and getting reinforcements. But you might get lucky and have your latest drone-code work well enough to overrun the planet before a weakness is found. It doesn't work this time though. It rarely does against Peer Enemies.

Your next step is deploy the Space Marines. Their objectives will vary, but in general their mission will be either: A: To destroy the means by which your enemy delivers its counter-drone hacking. Maybe that's the destruction of mobile command centers (if your starship vs ground emplacement tech favors the spaceship) maybe it's assaults on hardened command bunkers. Or B:Class A civilization tech is so good that you'll never get all the hacking micro-satellites/broadcast centers unless you flat-out take the planet "the old fashioned way."
If the tech you decide is being used to hack drones is somewhat contained (the capture of Building X will stop drone hacks) then a follow-on drone wave (or the re-activation of Wave I) is deployed. Your opponents (also squishy biologicals because you're broadcasting your own drone hacks from orbit) realize the jig is up and either flee or surrender. If the drone hacking tech is all-pervasive on a planet you may never be able to effectively deploy drones at all until the entire planet (or multi-planet civilization) is conquered and they're turned off as part of the treaty, or you hang around long enough to patch your drones. Either way the war on the ground is won by normal infantry before you can deploy your Perfect Robot Soldiers.

The only other option I can see are covert insertion teams deployed under diplomatic cover or among refugees etc. But I would classify those guys as more "covert ops" than "military" in the sense that they're playing spy games with guns more than fighting a war.

Answer 3

They Are Neither Relevant Nor Cost-Effective

The cost of making a fighting robot that is much better than a human at war is nothing more than few hours of machine work. This is how everything gets done anyway from the simplest things to the most complicated. Humans barely supervise anything and all is done by AMI.

This is all that needs to be said to make it clear. Soldiers are expensive. As of 2013, the US cost-per-active-duty-member in the field was $158000. So the cost to put one pair of boots on the ground was approximately equal to that of a condominium, or a luxury sports car. So not only is the machine better at combat than a soldier, it's miles cheaper.

On top of that, fielding infantry in a dangerous space is terrible PR. Even if your propaganda ignores the deaths, enemy propaganda disseminated in your space will drive home how many wholesome Truxican boys and girls are dying for no good reason.

As in your other question, largely undifferentiated machines (Floating Interdiction Orbs) can fill the role. In the event that a human decision maker is needed for cultural, PR, or diplomatic reasons, they wouldn't be infantry, they'd be diplomats or administrators, escorted by an honour guard of cost-effective, efficient, replaceable war machines.

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Additionally, though somewhat out of scope for the question, humans are squishy bags of mostly-water. This means that transporting human infantry has to take that into account. Dropping them from orbit requires slowing at accelerations that don't involve breaking bones or driving brains down one's spine. Robots don't have this problem, particularly if they've been designed with this in mind.

Their delivery systems are more maneuverable and less subject to being shot out of the sky - and if they are shot out of the sky, you lose less. And you don't have to spend a ton of money on life support.

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Additional addendum:

Personally I thought of having some people still choose to be infantry, but as either officers wanting to gain more experience or insane zealots that the military sees fit to throw away in the nearest conflict.

This is unlikely in the extreme, because anyone who wants to be in combat is not a weapon a commander would want. Officers are largely irrelevant (and infantry "experience" wouldn't be necessary), and all the arguments about the cost of soldiers means that shock-troop "zealots" would be both less effective in battle and less cost-effective. What military would want that?

Answer 4

Sure! As long as the ratio of money-to-common-sense is high enough.

In many ways this is a story-based question. Do you want an infantry? Have one. You don't need to justify it. But can it be justified? Of course not. Who in their right mind would land tens if not hundreds of millions of anything (infantry, drones, mechs, anything) on a world?

You'd gas the place. And with the kind of tech you're talking about, it would be trivial.

Author L. Ron Hubbard figured this out decades ago when he wrote Battlefield Earth. The Phsychlos didn't drop people/mechs/anything onto the planet until after they'd gassed the place into subservience. "Infantry" (or anything else) would be used only at the very end to clean up the handful of hotspots that might exist.

And if you don't want to gas the planet, you'd use drones. Now, a justifiable reason to not use drones is because the signal could be jammed (that doesn't seem to happen much when drones are used in the world right now, but tech tends to be the great equalizer... so maybe in the future...).

So, you don't want to gas and your world's version of the Taliban has signal jamming tech, so no drones. That means boots on the ground. Which almost justifies mechs...

Except that mechs are the worst tech in the known universe to bring death to your enemy. Orbital bombardment would be cheaper. Except you likely don't want that. Tanks would be more useful (fewer weak points, like knees). But there are people in the world that simply demand mechs!

Except that mechs are limited. They require fuel and are easily attacked by semi-hidden people with anti-tankmech weapons.

Which brings us to infantry. In a mobilized military one of the purposes of the infantry is to protect the mobile armor from semi-hidden people with anti-tankmech weapons.

So, other than nobody in their right mind would pay to take a planet with anything as expensive as infantry, tanks, mechs, planes, etc. (i.e., they'd gas the place), you'll always have the need for infantry. Boots on the ground to clean up the situation when all the expensive toys have been shot down or used themselves up.

Answer 5

I see at least two situations in which human soldiers would still be useful:

1. Special Forces/Commandos: You specifically mention that your A.I. is not on the level of humans, which opens up a window for highly trained elite soldiers that are able to perform missions that robot-grunts might be too stupid/uncreative to do (taking out crucial targets behind enemy lines etc, sabotage, assassination etc...).

2. Occupation-forces. Robots and drones might be good at wrecking things, but without advanced A.I. they don't make for good occupiers, at least if you want to keep collateral damage low, because you need at least some police- and social skills.

Answer 6

Humans can move around without raising suspicion

Since you say that all humans are essentially on permanent, 100% welfare, they are free to do what humans with free time do: waste time. So watching humans come and go from planets is business as usual since they have free time and free resources.

Now, whenever you see war-ready bots rolling around, you assume they're there to either protect or attack, and you know something might be going on. Then everyone pannicks and your targets will most likely disappear without a trail.

BUT if you use the advanced human infantry, more like a tactical team like the SEALs, you can have them move from planet to planet almost unnoticed, and that way get to your targets sooner. Yes, they are not "infantry" in the cannon fodder sense, and not many people are needed, but they still make a good chunk of the army.

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Now, everyone is on welfare, but that's only for survival purposes. If you want anything else (luxury items, being able to travel to the most beautiful planets, the ability to have more than X children - or have children at all) you must provide some service to the Government. Being a SEAL is just one of those services.

Answer 7

Have computer technology vastly favor decryption over encryption

The concept being presented here is fairly simple. If in your setting virtually anything electronic that is not sitting in a faraday's cage can be hacked, then the old-fashioned infantry is going to make sense again. Now, the means of achieving total decryption>encryption imbalance is a bit nebulous as this author happens to be terrible at computer science, but it should not be hard to handwave in.

also, note that this solution still allow some drone warfare, you could still have drones doing simple repetitive jobs like patrolling or search&destroy as long as they're sitting in a faraday cage