This is an interesting question, but I think a bright-line distinction is fairly easy to make.
It's not unethical to try to influence someone, even subconsciously, even by the choice of arbitrary design elements ("you start with 2 of 12 checked") -- as long as there's no deception. Introducing deception crosses the ethical line. So faking a purchase that was never made to gain a benefit is unethical.
Perhaps there's a bit of grayness in that the 2/12 stamps makes people prone to underestimate the magnitude of the remaining effort ("5/6ths remaining") compared to an absolute measure ("10 of 10 purchases remaining"). But without there being a misrepresentation -- for example, a claim that the first 2 stamps are a special favor not usually granted -- all info for a proper evaluation is available and truthful. And it's even possible that such an influence is to the consumer's net benefit: maybe there's another cognitive bias against completely-unstarted efforts, causing people to overestimate effort required and never get started on things they'd actually enjoy. In any case, once the alternatives start requiring discussion or even controlled study to evaluate, it's harder to apply a stark label like 'unethical'. That label is more useful on easier-to-evaluate actions like prima facia deception.
(Still, the point is well taken that these are some sort of continuum, and it might be the case that a certain superficially-truthful offering is so likely to be misinterpreted by an average reader/listener that it is still de facto deception. I don't think the reward-stamps case is anywhere near that line... but carefully-wordsmithed political ads, designed to create false impressions without being blatantly falsifiable, often go right up to and over the line.)
> It's not unethical to try to influence someone, even subconsciously, even by the choice of arbitrary design elements ("you start with 2 of 12 checked") -- as long as there's no deception
I feel your statement is too pat. Why is that not unethical? Based on what ethical pattern?
If the basis of ethics is being truthful, it would seem that ease of understanding is also an important part of ethics. Subconscious manipulation and influence seems to be at odds with that goal.
Perhaps such manipulations is inevitable in a marketplace where everyone engages in unethical mental manipulation, but that does not make it ethical.
But do we even know the 2/12 variant is worse on "ease of understanding"? Maybe it's more understandable, and congruent with the buyer's real best interest, because it's not subject to an endpoint/inertia-of-zero bias that depresses sales from the 0/10 case.
Note that these same sorts of perceptual influences are also the basis for all the do-gooder initiatives that get proposed by Richard Thaler and Cass Sunstein in Nudge. (So in fact I would grant there is at least one more dimension beyond deception: is the influence clearly against someone's interest? But there should be no presumption that whatever they would have done without the influence was the purest expression of their interests.)
Part of my ethical criteria is: what rules work? Part of 'work' is that they are evaluable. An accusation of undue influence, even though every observable aspect of a communication is true and fully disclosed, is very hard to evaluate. It's not very useful as a rule for deciding what one can do, or for assessing 'guilt' after the fact.
Using a bit of communication that is false on its face is easy to evaluate. It's fraud, and it's clearly unethical.
'Manipulation' is a loaded term. It just means "influence we don't like". In a commercial setting, reasonable people already assume a seller is crafting their communication to increase sales. Calling cleverly-crafted commercial influence 'unethical manipulation', even when it remains true in all observable aspects, overloads and dilutes the idea of what's ethical.
Is A/B testing that results in color, wording, and layout changes that increase sales 'unethical manipulation'? Perhaps if it goes so far, in total effect, as to create a tangibly false idea in the customer's minds. But not simply because it incrementally nudges someone towards a purchase.
It's not unethical to try to influence someone, even subconsciously, even by the choice of arbitrary design elements ("you start with 2 of 12 checked") -- as long as there's no deception.
In the simple case this is usually true, but I do wonder when you start throwing millions of dollars at researching exactly this sort of influence and start looking at pavlovian trigger mechanisms and stuff like that.
Most people aren't trained confidence tricksters, stage magicians or professional psychologists, but modern marketing at its most sophisticated is the combination of all three, backed with vast wealth and global reach, and it has already long gone beyond any pretence of acting as a way of informing people of things they might like to buy and has instead attempted, with a lot of success, to become the product itself. And, in case anyone was in doubt, I do not entirely regard this as a good thing.
It's not unethical to try to influence someone, even subconsciously, even by the choice of arbitrary design elements ("you start with 2 of 12 checked") -- as long as there's no deception. Introducing deception crosses the ethical line. So faking a purchase that was never made to gain a benefit is unethical.
Perhaps there's a bit of grayness in that the 2/12 stamps makes people prone to underestimate the magnitude of the remaining effort ("5/6ths remaining") compared to an absolute measure ("10 of 10 purchases remaining"). But without there being a misrepresentation -- for example, a claim that the first 2 stamps are a special favor not usually granted -- all info for a proper evaluation is available and truthful. And it's even possible that such an influence is to the consumer's net benefit: maybe there's another cognitive bias against completely-unstarted efforts, causing people to overestimate effort required and never get started on things they'd actually enjoy. In any case, once the alternatives start requiring discussion or even controlled study to evaluate, it's harder to apply a stark label like 'unethical'. That label is more useful on easier-to-evaluate actions like prima facia deception.
(Still, the point is well taken that these are some sort of continuum, and it might be the case that a certain superficially-truthful offering is so likely to be misinterpreted by an average reader/listener that it is still de facto deception. I don't think the reward-stamps case is anywhere near that line... but carefully-wordsmithed political ads, designed to create false impressions without being blatantly falsifiable, often go right up to and over the line.)