Imagine a world in which humans are exactly as they are now (size, strength, male/female, etc.), but were completely emotionless, the mind always feels "flat". These humans would have no reason to do anything other than eat and drink to live, and even those things they would have no emotional drive to do.
How far would they go technologically? Would they still do things like farm? Would these humans be able to sustain a society without the drive to live and reproduce?
Modern research has found that behaviours aren't simply related to emotions, they are driven by them. People who have suffered brain injuries which damage the emotional centres of their brain lead to unexpected consequences; mostly that they can't make a decision. At all.
When presented with a choice, they will attempt to rationalise the choices, as they lack the emotional driving force which leads most people to a quick "gut feeling". Like, I want fish tonight.
But when it comes to specific questions, people suffering problems in this respect are almost paralysed by indecision and the need to weigh possibilities. What sort of chicken do you buy? Breast, fillets, diced, whole chicken? Okay, you don't know what you feel like, so what is the most cost effective choice? But the whole chicken is on sale. So how does that change the calculations? As you can imagine, it makes even the simplest decisions we usually give almost no thought to, extremely problematic. Someone without emotions suffers from a severe and crippling disability.
So I'd advise instead of asking, what would society be like without emotions, perhaps you should ask what would society be like if society expected individuals to contain and control their emotions. Star Trek's Vulcans are the obvious example to reach for, but they're just one representation of that idea.
In this case, you get a society driven by calculated rules and values, but the question of what set of morals influence these rules is pretty much up to you and highly context dependent.
If you are asking "how would the people of the world survive if everyone lost their emotions?" then the short answer is very badly very quickly, as people would remember that they could feel but are no longer able to express what that was (as they cant feel anything anymore). I imagine a lot of people would go mad as their minds get stuck in a strange logic loop of trying to emote without emotions or describe feelings without using other feelings as a reference point.
However if people had always been this way, I imagine they would do very well for themselves. With personal happiness becoming irrelevant, collective survival would be the common goal, creating a race of hyper-communists. From the dawn of time on the plains of africa fighting ancient lions to the modern day, people would logically see that helping everyone in the most resource effecient way is to the benefit of all. There would be no happiness or pride to be achieved from personal gain over others. Overpopulation would not be a problem as the people who cannot contribute would volunteer to be killed for the benefit of the others. Morality would not exist (at least not in the same way as ours), and so advances in science and medicine could advance unimpeded. Art, music etc. would only be used for practical design purposes and limited to what was most efficient. Almost everything would be square or round, depending on if it is to stay still or to move.
Farming is a logical way of producing food and would be made as efficient as possible. Therefore warmer countries would likely be made into giant farms to produce food for the world population while colder countries can be used for more logical things like server storage, making them giant data warehouses.
You may want to determine when/why/how this came to be because, as others have implied, it might not lend itself to survival. Was this a cultural phenomenon or some type of evolution or a reaction to some world event. Knowing the origin might inform how it would play out down the line. For example, I heard a study about a group of primates (I think gorillas?) that had very aggressive pack leaders. But then they found some tainted food which the pack leaders hoarded aggressively and so they were the ones most affected and the aggressive ones died. This led to the less aggressive males being in charge and so the whole group dynamic changed. Even when aggressive males came in, the majority were non-aggressive so the new male would adapt to that.
I would have to think that you would need to distinguish what level of emotion you mean. I believe that at its core all human needs are emotional. The desire to eat, procreate, the will to live are all emotion. And/or conversely, emotions are all manifestations of some instinctual need. We would breath and blink and our hearts would beat because those are automatic. But if this was a cultural convention things might not be too different than now because in essence emotions and there fore motivations still exist and things would happen for seemingly logical reasons, but in reality they would be emotional reasons.
You know why every single creature on this plant wants to live ?
The answer is simple
living beings with no will to stay alive simply die and go extinct
To not die and go extinct everyone needs a reason to stay alive or a reason to avoid death and survive.
No fear: This is the most basic and powerful emotion of every living being even humans. Without it Everyone dies. Every single decision we make influence our entire lives permanently in a chain effect and they can't be changed, fear and anxiety gives us a reason to make the most reasonable choice, if they manage to survive without fear, they might as well all be retarded, even plants and bacteria need fear of death to stay alive.
No courage: Everyone dies in stupid ways, and everyone becomes a coward with no pride, Why should I eat that plant? It could kill me in an incredibly painful way... better starve to death, Why should I defend myself from this big cat with point teeth? Resistance could be more painful than just letting myself being eaten alive.
No Love: Some people will not have will to live and reproduce or do anything. Some people won't be affected by it too much...
No empathy: killing and torturing random people at any time would be considered moral, though this doesn't make much of a difference, religions already have this same effect of moral destroyers.
No happiness: Not being able to feel pleasure gives us no reason to do anything at all, I want to kiss someone, but why should I do that if it makes me feel nothing? I want to find food and eat so I can survive another day, but why? I want to have kids so I can build a family, but why? I want to keep breathing so I can stay alive, but why? If there's NO emotional reward, there's no reason to do anything at all.
No sadness: Not being able to be sad makes you not care of anyone and lose your ability to feel empathy, love. Why should I not destroy your dreams or kill your family for my own interests if it doesn't damage you at all? I won't care cause neither me nor you will be sad about it?
No emotions altogether: With not any ability to feel anything from the above, we wouldn't be classified as living beings... we would be objects and our lives as meaningless as rocks.
You see ? We need emotions to make decisions, we need to make decisions to be human and we can't even exist without being able to feel any emotion at all...
Perfect place for ripoffs.
Nobody would hold a grudge. Nobody would fight back, because the risk of being killed makes it not worth it. Nobody would make an effort on behalf of the group, because why would they move? They don't have a sense of duty or anything. They'd only fight back if they have more to gain for themselves.
An easy prey for any warrior race.
For one thing, dating would be simpler, as the only drive would be pleasure, which isnt really emotional.
I suspect there wouldn't be any forms of discrimination as there'd be no hate.
But it depends, because pleasure is associated with feeling good... but they can't feel... which leaves you in a nice paradox which i'll let you solve
