1: A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2: A robot must obey the orders given it by human beings except where such orders would conflict with the First Law.
3: A robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.
Get it? Got it? Good.
Aliens is my favourite movie, something I have established before - and it is my not very humble opinion that it is a far more clever movie than it lets on. There's several world-class performances in this movie, and not just from the principle main cast too - perhaps one of the best performances in this movie is put in by the legendary Lance Henriksen, in his portrayal of the (spoilers) android, Bishop.
Let's talk about the first time we really meet Bishop - no, not when he walks past out of Cryo.
No no no, when we MEET him. In THIS scene, in the mess hall, right here.
See, this scene establishes character and setting, and it does so with great subtlety. It does so without you even realising it is happening, because these people are just playing out their roles, right? They're just being the people you know they are.
So let's review.
In this scene, we have all the non-commissioned Marines dining together, while the Lieutenant decides to eat on a separate table with the two civilian contractors - a fact that is noted, and interpreted as aloofness. This is an assumption that carries through until it's revealed that he's not really aloof - he's just inexperienced, and has no idea how his soldiery would perceive him doing the very basic thing of eating with Burke and Ripley. After all, none of the Marines want to eat with the civvies - and they'd just have to sit there by themselves. So it's the right thing to do to keep them company, right?
As much of an asshole as Hudson can be, he still respects Sergeant Apone, referring to him as "Top" when he enquires about the mission - but Apone doesn't know, so he spins a joke about colonists and their virginity. A further divide between the soldiery and Ripley in particular. This is a hyper-macho social environment, and it remains to be seen whether or not these Marines are all talk or not; an impression further portrayed by Frost and Hudson slapping hands over "Arcturan Poontang". Spunkmeyer has a smart mouth, but Hicks replies to his derision regarding the food with fatherly advice, humorous or not: "It's good for you, boy, eat it."
As this happens, in the picture above, we can see Bishop offering people food.
This is easily seen as his job - we don't know who or what he is yet, but he's been established as not a soldier (he's not sat with them) but not quite a distant civilian (not sat with them either) - and also, he's interacting with the troops directly, quietly, socially, positively - but in a subservient role. Everyone else has gone to retrieve their own main meal, but here he is, handing out cornbread to people and not, himself, eating.
And then this happens.
"Bishop, do the knife thing, man."
Further character establishment. Specifically we establish that Hudson is a clown, and that the Marines know Bishop, and have known him for longer than their new Lieutenant - no shared experience with them, but this is an event that has happened with Bishop and the Marines before. Hence the cheers and jeers from the others, until he caves in and...
Later - when the scene has played out as we all know it does - Bishop explains to Ripley that he cannot "harm, or by omission of action allow to be harmed, a human being", which is almost word-for-word a repeat of the First Law of Robotics. He states it is part of his behaviour inhibitors, which Ash - from Alien - simply wouldn't have. Perhaps due to what happened in Alien, even if the events of the movie are officially denied by Weyland-Yutani, or perhaps due to other events wherein the "twitchy" Hyperdyne 120-A/2s have hurt people.
Now if Bishop just outright said "I can't hurt you, I'm not allowed," then this would be a throwaway line - but he phrases it in almost exactly the same way as the First Law is written; and if he is encoded with the First Law, then it isn't a huge assumption to believe he is encoded with the Second and Third laws, as well.
So what happens in this moment is the Second Law is invoked - Bishop must obey the instruction given to him by a human, even if he initially resists - despite the fact that it can cause him physical harm, because the Third Law implicitly gives way to the Second Law. So of course he will relent, and of course they know he will.
As this goes on, Drake and Vasquez, in left of shot, exchange a look - she slaps his arm and he gets up, wandering back behind Bishop casually and up to Hudson's left hand side. I like this look, because it's clear throughout the movie that Drake and Vasquez are very close, having a bond over and above that which is shared by anyone else in this unit, and one that appears to also be entirely platonic.
Then he does this.
For one thing I love the fact that Hudson grumbles at Drake for what he is doing - clearly indicating that as the class clown he doesn't appreciate being shown up by the far more confident and capable Drake - but his real surprise is shown by Bishop going along with it.
Another thing - see those brackets mounted into the table? All of the Marines are eating out of standardised lunch trays that fit into those brackets. Clearly this is a design nod to the fact that there might be a sudden shift in momentum or similar, or that artificial gravity may fail. Just a nice touch.
Here, though, could have been a moralistic dilemma for Bishop.
He's not allowed to hurt Hudson, directly or by omission of action, even if Drake tells him to - the Second Law can't subvert the First Law.
He could have refused the order, but that would also involve refusing Hudson's own order, which was made without any perceived risk to Hudson. Which he isn't allowed to do.
So he does the next best thing.
He puts his own hand directly over Hudson's, overlapping somewhat as Lance Henriksen actually has larger hands than Bill Paxton. Which is a good thing.
In this circumstance, he is obeying the First Law by placing himself in harm's way, so that the knife will harm him before it ever harms a human. In doing so, he is obeying the instructions given to him by both humans involved in this scenario - and he is invested in not harming himself as per the Third Law, which gives him further motivation to not miss.
We all know what happens next.
Look at their faces.
Vasquez and Apone are loving it - she knew exactly what Drake was planning. Drake is satisfied, amused by Hudson's constant terrified scream. Bishop is so focused on what he is doing that he doesn't have a facial expression. He's too busy not hurting himself (Third Law) OR Hudson (First Law).
It bears mention, as an aside, that this scene was shot as-is and sped up - and that while Bishop's knife trick was part of the script, Hudson's hand being involved was not. The entire cast and crew involved discussed the scene, how to do it, and agreed that Mark Rolston should be the one to force Bill Paxton's hand under Lance Henriksen's. EVERYONE knew it was going to happen...aside from Bill Paxton. So that look of terror is real. Even if the production knife is blunt, Henriksen stood a good chance of hurting both of them during the shoot. Of course Henriksen wasn't worried. He'd practiced this a lot.
Bishop gives Hudson his knife back, thanks him, and walks away. Drake puts the tray back, slaps Hudson's shoulder amiably and tells him to enjoy his meal. We're left with Hudson looking visibly shaken at his own uninjured hand.
Bishop walks back to the civilian table, offers the remains of the cornbread to those at the table, and then notices that he's nicked his finger in the showboating. Something it was entirely possible for him to do without actually hurting Hudson, given that his hands were bigger.
"I thought you never miss, Bishop," quips Burke. Which is interesting. It indicates he knows Bishop, or at least has heard anecdotal evidence of the already-established prior behaviour of the Marines and their accompanying artificial person. Arguably, he wouldn't have missed if he didn't have Hudson's hand trapped underneath his own - the necessity for protecting the person leading to a lapse of care in terms of protecting himself.
Ripley's following reaction is understandable - and Bishop's alarm at her fear of him, given that he knows he can't hurt anyone. Of course, she wouldn't know. She's been out of the loop for almost sixty years. Sigourney Weaver's acting in that moment is stellar, by the way - she glances, she realises what she is seeing, she turns to face the threat and leans back, head tilting back so far she is almost looking at him with sanpaku, her words of recrimination toward Burke coming out in a rush. It's a brilliant moment which is sold so well by Weaver that you can't help but feel her alarm yourself.
It's when he explains that he is bound by behavioural inhibitors to never hurt a human, and then rather tactlessly offers her some cornbread, that she loudly makes her feelings on the matter clear. Her precise words to him:
"Just stay away from me, Bishop. You got that straight?"
This scene alone is a goldmine for Henriksen's portrayal of Bishop. The hints all the way throughout this scene as to his nature, before the reveal of the white blood, should tell you what he is - and sets you up for the revelation, leaving you to just accept it. Of course he's an android. He's acted like one, he's been treated like one. Subconsciously the character has been set up for us to be the thing he is.
Further down the rabbit hole.
Ripley orders Bishop to stay away from her. It is done out of anger, out of fear, and out of alarm - she has an understandable suspicion of the behaviour of any android, let alone a company plant as she must suspect Bishop to be, given that he is canonically the spitting image of the man who runs Weyland Yutani in the events of Alien 3 (and presumably this movie, as the two are separated by almost no time whatsoever, perhaps a month maximum).
It is 55 minutes and 34 seconds before Bishop actually speaks to her again, almost an hour. Not to a group that she is a part of - directly to her. In that time the Marines have landed, they've made their initial investigation, found Newt, cleaned her up, entered the atmosphere processor, been ambushed, been almost wiped out, lost their Cheyenne dropship, lost their APC, witnessed Hudson's first breakdown, salvaged what they can from the wreckage of the APC, found out that they can expect rescue in two and a half weeks and witnessed Hudson's second breakdown.
He only speaks to her when the group are in a resource-restricted emergency situation. The group knowing what he is doing and where he is going is important, so there are no breaches of security, and so that his time can be efficiently used in treating a member of the group who is seriously injured and also trying to discover a way to defend themselves against the xenomorphs. Ripley's order to "stay away from me" (Second Law) is countermanded by her requirement to know what he is doing for the safety and security of the group as a whole (First Law), seeing as she has established herself as a competent leadership figure in the absence of the incompetent Lieutenant Gorman.
Likewise in a scene later, in which he is presenting his findings to the group - Ripley primary among them - he does so knowing that Ripley has shown discomfort and displeasure at his presence, but knowing that conveying the information he has is likewise important survival. It's at the end of this scene, wherein Ripley orders him to destroy the samples, that he lets slip an important bit of information.
"Mister Burke gave instructions that they were to be kept alive in stasis for return to the company labs...he was very specific about it."
This instruction he was given only gets brought up when Ripley gives him a conflicting instruction. That the samples could do harm to people isn't a metric that comes into it - fourth, fifth and sixth degrees of separation from harm done is a sticky area to get into in terms of absolute laws - but as he states later: he may be synthetic, but he's not stupid. So when Ripley states he wants them destroyed, he doesn't quibble. He immediately informs her of the vaguely potentially dangerous situation that Burke had ordered him to instate, and in doing so, forces her to resolve the discrepancy between the two instructions. He can't tell Burke no; that would break the Second Law, unless his action would directly cause harm. He CAN engineer a situation in which Burke can be forced by another person to rescind his instruction, and thus, he can conflict-free follow Ripley's instruction, which I daresay he is happy to do.
When it comes to the realisation that the atmosphere processor is set to explode, and the only way to get off the planet is to manually re-align a satellite dish at the far end of the complex, Bishop volunteers.
There's several reasons to do so. For one thing, as he says, he's the only person qualified to remote fly the second dropship from the Sulaco. He conversationally adds, after that statement:
"Believe me, I'd prefer not to. I'm synthetic, but I'm not stupid."
The balance of this is easy.
In the scenario presented, perhaps one of the marines would stand a greater chance of making it through the tunnel unmolested, reaching the satellite dish and doing the requisite technical work - Hudson has demonstrated significant electronic competency multiple times in the movie, further proven by him being one of the qualified motion detector operators.
As Bishop establishes, though - Bishop is a better choice to remote-pilot the vehicle, increasing the chance that it will land without incident and be capable of conveying the marines off-world. Also, if Bishop is ambushed and killed during his trip through the tunnel or while aligning the dish, then it is him who has died in the line of duty - rather than one of the humans.
He isn't qualified to fight. He literally rejects the firearm that Vasquez hands him, in a cinematic moment that I adore - she gives it to him without a second thought, as she is a Marine, and having a weapon to defend yourself with is second nature. He gives it back to Ripley, knowing that if it came down to pulling the trigger, he'd be dead already. The look on his face.
That's why he never volunteers for any combat operations - he would be more of a hindrance to his human team-mates than an asset, and would thus put their lives at risk more by his presence than his absence. In this scenario, though - the lives of all the humans are best served by him doing the job, a metric that balances the primacy of the First Law perfectly over his Third Law programming to protect himself.
The last thing he says before they close and seal the conduit behind him is to tell Ripley to watch her fingers, before he starts to shuffle down the crawlspace; Vasquez murmuring "Vaya con dios, man," as she welds the plate back.
He may be crawling down a two-hundred-meter choke-space tunnel toward certain death, but the last social interaction he has with the people who didn't even ask him to do this is to look out for the safety and well-being of the woman that previously ordered him to stay away from her.
In the scene earlier in the movie when Spunkmeyer brings some supplies to Bishop - who turns and looks at him in a vaguely creepy way, but Spunkmeyer's response is more akin to dealing with someone who is spacing out than an inhuman machine - wherein Lance Henriksen had suggested he wear special contact lenses to make his eyes creepy, to give him the appearance of inhumanity. James Cameron did a screen test for the scene and found that the way Henriksen played the scene out, from his coldness and distance to Spunkmeyer to his only really seeming to engage when he is studying the xenomorph under his microscope, was creepy enough.
That's the two ends of this character - a nuanced, textured individual who is a stand-out personality in a unit full of alpha gung-ho soldiers. A stellar job of character acting from a stellar actor. Both Henriksen in Aliens and Ian Holm in Alien put in simply breathtaking performances, for two different reasons - and of course, Holm's performance informs Henriksen's in terms of trying to make Bishop a counterpoint to Ash. No pretence of humanity, here - in fact, the only reason Ripley didn't know was because Burke should have told her but didn't. The Marines all know who Bishop is, and they like and respect him. He does his job, and they tolerate his personality quirks, and they trust his competencies as he trusts theirs.
Just another example of fantastic character from my favourite movie. Part of my reasons why it IS my favourite movie.