
You know it
Let’s get this out of the way up front; this is about Star Wars. We will take a look at the Force, its evolution as a storytelling device, and its viability as a religion as we understand it. So if this doesn’t interest you, you can go about your business. Move along.
I usually get ideas like this when I try to amuse myself by projecting myself as a fish-out-of-water in fictional worlds where my primary concerns are things like “How will I survive?”, “Where is the bathroom?”, and “Do I have to go back to Starfleet Academy and take Klingon Poetry 101 or can I just stay here on the Enterprise/DS9/Voyager where it’s far more exciting and do stuff like that Wil Wheaton kid?”
The Force, at this point, has rules that are well established by the first three movies, the second three movies, the Expanded Universe, video games, and various and sundry other branded properties. It has particular rules about its use, its capabilities, even the ‘alignment’ of several of its uses. For instance, something like Force Push (its official title, no less) is ‘neutral’ while Force Lightning is a ‘dark’ power (because the Emperor used it, and he’s, y’know, the bad guy) and Force Heal (which we’ve never technically seen in the movies, though what Obi-wan does to Luke when he faints…wait, that sounds wrong) is a ‘light’ power. People are limited in its use by natural causes, like one’s inborn connection to the Force, and through use, as users become tired after a time, in addition to being limited by their skill level or training history.
On a more practical note, characters are most limited by the needs of the story in question. For instance, users can Force Jump and Force Float (kinda like the landing part of Force Jump), but no one, to my knowledge, has ever Force Flown. Yet there are instances where this has kinda-sorta happened (The Courtship of Princess Leia has Luke floating down from the sky after falling out of his fighter, hanging there for a bit, and landing; Yoda practically does the same in portions of his fight with Palpatine) and there are instances where this would have been a rather useful skill had anyone possessed it (the Emperor’s tumble into the Death Star core, Anakin’s chase through Coruscant, Anakin’s fight with Obi-wan).
All of these issues brings me to a point where I asked myself: is the Force a deus ex machina? Is the the inevitable solution to everyone’s problems? As a storytelling device, does it undermine everything that comes before?
In addition to these questions, I was enjoying an interesting mental exercise involving “proving” one’s religion (as we like to have proof in science) and how one can even begin to have a theological argument with any basis other than “I think I’m right” when I had a thought. In Star Wars, they don’t have to explain it. They have proof right in front of their eyes. The Force exists, all in the form of its abilities: Push, Jump, Pull, Lightning. There should be no argument there.
Yet there’s a line from Star Wars that I find interesting given that supposition. Han Solo, en route to Alderaan, says to Luke, “Hokey religions and ancient weapons are no match for a good blaster at your side, kid.” Now, as far as retconning goes, at this point in history Emperor Palpatine has basically vilified the Jedi and the Force to a point where the common citizen of the Empire would believe that all of that was a fantasy or a delusion (despite thousands of years of history of the Jedi on countless worlds, but I guess everyone in the Empire just watches Fox News). But in the context of A New Hope only, the Force does take a rather different form than it has evolved to be at this point. Save for one or two instances, use of the Force leaves question to its existence to the characters in the story. Let’s go through them.

Sing, my angel of music!
1. The Meeting on the Death Star
In the only example of actual Force use we can point to that it is unlikely to be done any other way (and one of the places this argument is easily broken down), Darth Vader chokes an over-proud officer from across the conference table on the Death Star. As I said, this is the one of the few instances of the use of the Force in A New Hope that actually actively affects anything in the world. Most of the other instances are of a “sensing” or “mental distraction” sort of thing. A skeptic’s argument might be made here that all Imperial officers (or, at least the ones within the Emperor and Darth Vader’s purview) are equipped with uniforms whose collars will constrict upon command as a form of control and fear of one’s superiors (unknown to the officers themselves, of course). Given the level of tech in Star Wars and given the fact that the officer actually attempts to loosen his collar (which should have no effect on an invisible force closing your windpipe), it is within the realm of possibility.
By the by, the other instance where Vader chokes someone (the Rebel officer on the Tantive IV at the start of the film), he actually physically chokes with his hand and lifts him off the floor. Since Vader should be able to use the Force, it seems rather uncharacteristic of him to actually physically throttle an opponent (who doesn’t wear a special uniform), save for the visceral thrill.

Smooth operator
2. Kenobi talks his way past the stormtroopers
Luke and Ben arrive in Mos Eisley only to be detained by stormtroopers inquiring about their droids. When the conversation doesn’t start to go the way of our heroes, Kenobi uses the Force to “suggest” to the troopers that “these aren’t the droids you’re looking for” and that they “can go about their business”. From the skeptic’s point of view, as with the choking scene on the Death Star, this is one of the points in the movie where the Force does seem to be the only reasonable explanation, especially considering the stormtrooper’s dutiful repetition of everything he says. However, there are other possibilities. The most likely is that Kenobi is flashing a couple of credit coins of large denominations in his other hand (which we can’t see), and the little motion he makes with his hand is a galacticly-recognized sign for “I’ll pay you to let us go”, kind of like the “thumbs up” gesture is a world-recognized sign for hitchhikers. Ben drops the coins out the side of the speeder before they move away and the trooper and his mates are a few hundred credits richer for their trouble. As far as Luke is concerned (he doesn’t know the sign, having never been off-planet), it’s a rather fortunate turn of events, all orchestrated by Kenobi.

The Wookiee's with me...
3. The Bar Fight
Here, Ben Kenobi draws his lightsaber, maybe deflects a blaster bolt or two (hard to tell from the movie, though the novelization does imply that he does) and chops off the assailant’s arm. Given our current understanding of the Force, Ben senses that the assailant is going to attack, draws his lightsaber, senses where he’s going to fire, deflects the bolts, and ripostes. From the skeptic’s viewpoint, he gets lucky (and, at that range, it is possible for him just to put the blade in front of the muzzle of the blaster and be effective) and attacks like any other skilled swordsman would by disarming (ha ha!) his opponent.

Sha-wing!
5. Deflecting the remote bolts and sensing the destruction of Alderaan
On the Millennium Falcon en route to Alderaan, Luke is having little luck consistently deflecting stinger bolts from the remote with his lightsaber. It’s only after he can’t see with the helmet blast shield masking his vision that he somehow is able to do it well. We know that he “senses” the position and intention of the remote using the Force and is able to effectively block three bolts. From the skeptic’s view, he just gets lucky or Kenobi has fiddled with the remote (luck seems to be Solo’s conclusion as well, sitting less than 10 feet away from Skywalker).
Also in this scene, Kenobi senses the destruction of Alderaan (though it is not the screaming, throwing-up ordeal as described in I, Jedi). Being attuned to the Force, he is able to sense the violent deaths of billions at the same moment (though arguably, in a galaxy as large as the one in Star Wars, at the very least millions die violently every single day). From a skeptic’s perspective, he is simply lying to get attention, or he’s having a headache and is finding divine inspiration in that.

Dude, Amazon does NOT ship to the Death Star next-day air...
6. HE is here
Vader reports to Tarkin that HE is here, referring to Obi-wan being on the Death Star. At this point in the continuity, Vader hasn’t seen Kenobi in twenty years, and at least Tarkin assumes that he died at some point during the Great Purge, otherwise he would have challenged Vader again in the intervening time. In this case, one could say that he senses Kenobi through the Force, like a moth leaving a trail through smoke. The alternative explanation here is that Vader is doing some inspired guessing, in part because an empty ship doesn’t just happen upon the most powerful battle station in the Empire that just-so-happened to recently destroy an important ally of the Rebellion simply by chance. It’s also possible that Vader routinely blames his old master for everything under the sun(s) (“No Vader, I don’t think Kenobi took your night-light. Yes, I’ll get some stormtroopers to go look for it. Now go back to bed.”), which is why Tarkin is only mildly interested in Vader’s insistence that Kenobi is on board. On the other hand, Vader does seem to know at least in which direction Kenobi is, so unless he’s checking every bathroom on every floor in the Death Star, he’s going to have something of a hard time finding Kenobi. On the other other hand, Vader knows that the princess is pretty well guarded, so he could be making the next logical step in assuming that Kenobi plans to escape and would need to disable the tractor beam and return to the ship, and there are probably only one or two ways from the tractor beam generators to the hanger bay.

The Tic-tac: a stormtrooper's favorite treat!
7. Kenobi distracts the guards
Kenobi has just disabled the power to the tractor beam and he sees two guards on duty. He gestures with his hand and the guards think they hear something and go check it out. Using the Force, he puts the suggestion in their minds that they heard a sound that they should go investigate. On the other hand, it’s possible he just throws some nicknack in their general direction that does actually make some noise that we can’t see (say something the size of a small ball bearing). Confusing the entire affair is that (if I recall correctly) there actually is a little ‘tink’ noise on the soundtrack at this point! If it’s a mental suggestion, we (the audience) shouldn’t be able to hear it. On the other hand, it could be Kenobi actually used the Force to move something out of place physically to make that noise, as an alternative to a mental suggestion.

I see your Schwartz is as big as mine!
8. The lightsaber fight
Kenobi and Vader have a rather prolonged lightsaber fight during the escape from the Death Star. The in-universe explanation is that, in addition to being experienced swordsmen, the pair use their abilities in the Force to sense the strikes of their opponent and block and parry with great skill. The skeptic’s view is that they are, in fact, both skilled swordsmen and this is the exhibition of their abilities. Also, like chess players (to which they are oft compared), they are not only interested in defeating each other (arguably Ben doesn’t actually want to kill Vader, but Vader definitely does want a piece of Kenobi) but they are also interested in testing the extent of each others’ abilities. This is why the fight doesn’t end as most sword fights really do: within moments of their beginning.

I've set my lightsaber to "extra crispy"
9. Kenobi disappears
This is the most damning example of the ‘reality’ of the existence of the Force in the entire film, even more so than the bluffing in Mos Eisley or the Force choke on the Death Star. There really isn’t a good explanation for this save for the fact that the bodies of Jedi Masters disappear upon their death. The only ones I can offer are that, for one, the movie could be seen as being recalled from the perspective of either the droids or Skywalker (as we are rarely privy to information outside their knowledge or, at least, their ability to surmise after the fact) and that, from their perspective, all that was left of Kenobi that they could see was his outer robe (which hid the two parts of his body going their separate ways), but that’s about as apologist as it gets. As for an in-universe explanation, it is possible that lightsabers vaporize flesh very easily when they’re turned up to a higher power setting, in contrast to a lower power setting that only cuts (as Ben does in the bar). Once again, the evidence for this sort of thing is pretty weak. And why does Vader toe Kenobi’s empty robes? Maybe he needs some change for the vending machine down the hall?

What you can't see: the sign that says "WARNING: do not smoke near the exhaust port - contents are explosive"
10. The needle that popped the Death Star and the voice from afar
At the end of the film, Luke turns off his targeting computer and successfully blind-fires two proton torpedoes into the exhaust port, destroying the Death Star. Using the Force, Luke senses the proper angle and moment at which to fire his missiles. On the other hand, he (again) gets lucky, though not without reason. His practice at shooting at womp rats in his T16 on Tatooine (which probably didn’t have any fancy target computers in it, but rather just iron sights or their Star Wars equivalent) was practice for situations like this where other pilots, who were typically accustomed to larger targets and the benefit of targeting computers, would fail.
As for the voice from afar (which does manifest several times before this), it is possible that the combination of the stressful situation (escaping the Death Star, on a mission to destroy it), the loss of several people who are close to Luke (his aunt and uncle, his father’s long-lost friend), the massive changes in his life in such a short period of time (going from a quiet farmer’s life to traveling off-planet, evading and attacking the army/police, killing other people), in combination with Ben’s stories of the Force may point to the possibility that Luke is just making it up and talking to himself as a method to cope. I’ve actually seen something similar to this happen to someone I met on a trip in another country; he was so overtaken by being in a foreign place and away from home from the first time that he had a nervous breakdown. In fact, Luke’s mental fortitude is pretty impressive when you stop to consider his situation, especially in comparison to the other characters’ experiences that allow them to cope far more readily. For a person with basically zero downtime between these massive, life-changing events, he’s doing pretty well if he’s only hearing a dead man’s voice in his head.
And?
Given these (conveniently) ten instances of “Force use” which stand on relatively shaky ground in comparison to explicit use of the Force in the next few films and Expanded Universe (Luke pulling his lightsaber to him on Hoth, levitating the X-wing on Dagobah, jumping all over the sail barges on Tatooine), we can say that the Force isn’t quite the thing we thought it was, at least in the context of A New Hope. It’s more enigmatic, and it’s only demonstrably real to those who believe in it or those who are impressionable, but the “common” person like Solo just doesn’t believe in it. One can make valid arguments (as I mostly have here) given these examples against the existence of the Force, that it could be more of a way of life, a belief, and a faith than a practical part of the universe like electricity, magnetism, or gravity. Like many faiths, it empowers its believers (you get to do special things!) and makes a place for all the unbelievers (oh, he’s just not Force-sensitive).
I rather prefer this version of the Force, where it’s not-quite-real, in part because it gives the characters some room to breathe and it doesn’t solve all their problems. As a codified ability (which it has become over the years) it loses all ability to be fallible, requiring yet more outlandish excuses for Force-users’ inability to win the day outright every time (the ysalamiri come to mind). In comparison, one’s special powers in The Matrix relied on one’s ability to mold and shape their mind to realize what their experience really was and how to change it. It’s like learning to stop breathing; it might be possible, but everything in your autonomic nervous system is screaming at you to draw that next breath, even though, in the Matrix, you don’t need to breathe. It’s not easy. The problem with the Force is that it really is too easy. It has no practical limit if you submit yourself to it, up to the point where characters are tossing around fleets of Star Destroyers.
Now I hope it is obvious that this is hardly a serious argument against the existence of the Force in A New Hope, but rather a fun experiment into changing our assumptions of what people like myself, who saw the original trilogy as a set as opposed to three separate movies, view as the original intention of the author. Admittedly, save for a few instances, it does seem plausible that my argument holds water, so one could say that it was the original intention of the author to have something more mysterious and less explained, which is one of the great things about Star Wars in general. It didn’t require long-winded explanations of the workings of the universe (save for the opening crawl, which is an amazing construction that encourages the audience to read it), but rather dropped you in and let you fill in the action off-camera. Contrast this, of course, to the reams of expository dialogue in other films, including the second trilogy, which makes the experience a far different one from the one we came to enjoy.