Say Alice invents a new product and launches it.

Bob has a time machine. Let's assume he can go to the past and his actions change the course of events after this moment in the past. (Very hypothetical, I know.) He goes back to a time before Alice invents her product, he patents the idea of Alice and launches it on the market.

Now the product is launched before Alice would has invented the product and now e Alice would either

  • never invent the product because before that could take place she has already heard of the product
  • "Invents" the product, but finds out the product already exists. (Just like so many ideas of so many people.)

Are the actions of Bob unethical or not, according to the frameworks of situational ethics and utilitarianism? My feeling is that it is, but I don't know the exact reason. On the one hand, Bob got the idea (stole it?) from Alice. On the other hand, Alice invented the idea when it already existed.

Instead of a product idea, I also consider any idea in general.

  • 1
    Depends on the framework. Please specify as the question as it stands would need consideration of tons of different theories to reach something even close to objectivity.
    – Philip Klöcking
    Jan 16, 2017 at 17:56
  • The frameworks I'm considering the most are situational ethics and utilitarianism.
    – Kevin
    Jan 16, 2017 at 20:23
  • 1
    The time travel element makes the question seem intractable, but upon closer inspection, the scenario is no different than regular industrial espionage scenario - so the basic ethical analysis that drive patent laws and intellectual property laws would apply. Jan 16, 2017 at 21:51
  • In terms of Utilitarianism, whether it's a good thing or a bad thing depends on several factors as far as I can tell. Is it a really good product, that will increase utility, and therefore would be better to have it exist sooner? Who is more in need of the money that would be earned from the product, Alice or Bob? Just in terms of Utilitarianism, I think those would be the details you would have to know to know whether what Bob did was moral.
    – monster319
    Jan 17, 2017 at 12:35
  • depends, is it a sitcom or adventure? i'm voting to close, tho really just cos i felt like being arbitrarily humourless. peace :)
    – user6917
    Jan 17, 2017 at 17:15

4 Answers 4


I am going to begin by assuming by utilitarianism, we are taking our goal to be "pleasure" or perhaps "happiness" for the most people.

Time travel is actually relatively unimportant to answering your question, but we need to answer two questions about the metaphysics of time travel before we can answer the question about inventing future products before their original time:

  1. Can we fully grasp the effects of our time travel? (Here, I mean specifically can we know what this will do in terms of pleasure in our present and in our past / future).
  2. Do we weight future happiness as equivalent to present happiness?

The reason is that among contemporary utilitarian views, there's a few debates that interface with these questions:

First, are we maximizing expected happiness or realized happiness? In other words, is it the intention of our actions towards happiness producing or their net effects. To give an example, if I walk into a room with a bag of poisoned candy and plan to hand it to children to kill them, then I have a goal that is evil in terms of intent. If it turns out by accident that I saved all of their lives from the poisoned water, then I've had a greatly positive effect, and my action was good. Conversely, if only intent matters, then the actual effects are irrelevant.

Thus, if we assume that we can have full knowledge of our effects, then the right/wrong calculation shifts accordingly, and everything trivially follows. If we can't know but we need to know, then our hands are tied as to making these sorts of actions. If we don't need to know, then the answer to 1 is irrelevant.

Second, The answer to 2, however, matters in that we need to know if our calculus cares about future happiness, present happiness, and past happiness equally. To borrow an idea from another debate, are we A-theorists or B-theorists about human happiness (Cf. McTaggart and time)? In other words, is "now" privileged or is "now" equally valuable with all other moments. If A-theorists, then we have quite a few calculations to make, and we will need to figure out which timeframe's utility concerns us the most. If B-theorists, then we either need knowledge as per our response to first.

Third, there's a further issue about whether we think every moment should calculate the right/wrong of an action de novo or whether what we want to do is establish rules that are happiness-maximizing and follow these (this is the act vs. rule distinction suggested by R. M. Hare).

If we are rule utilitarians, then the rules apply equally well whether we can time travel or not. And what might need adjustment is possibly our knowledge condition -- if we can time travel, then our knowledge condition would probably be pretty strong, because we could evaluate the happiness outcomes of the things we attempt.

Looking at your example, there's by and large nothing special about this case unless we have eccentric answers to 1 and 2. In other words, it seems no different from stealing in the present if we are rule utilitarians and no less in need of a happiness calculation if we are act utilitarians (with whatever conditions we have on the knowledge-intention divide).

An issue that may gum up all of this is is the idea the time travel is on parallel world lines rather than an identical one. Then, we must resolve how much we care about happiness in each world-line, and whether we privilege our own. But again, the time travel aspect in a sense works itself out rather than being a major concern for the morality of our actions.


Ethics is always a difficult one. However as far as utilitarianism goes then, under the assumption the product makes some job easier, by travelling in time Bob is providing this ease to more humans. He is, therefore, providing a greater good which supposedly surpasses that just of Alice. (Utilitarianism ignores the fact Bob does this for his own selfish means).

We are, however, stuck in not knowing the effect of this playing with the past we are doing. Initially we could consider it as copying an idea from a hermit inventor and spreading what he makes to those who would never meet him. With the inclusion of time-travel this has been complicated in several different ways.

1) What effect does this have on Alice? Perhaps her first success sets her off on a journey of discovery which ends up saving millions of lives...or perhaps her first was a fluke and her next invention goes terribly wrong and explodes, demolishing the building she was working in. The point is we cannot predict this and so some extra element of risk is taken on by Bob.

2)Time-travel is rather a sticky subject, perhaps Bob would create a paradox which tears apart the universe (not very high up on the utilitarian to-do list).

3) If Bob is in a position to travel in time and he chooses to use this opportunity merely for personal gain he has chosen not to save many many others. He could warn Japan to evacuate Hiroshima and Nagasaki, he could warn the US of 9/11, he could do the cliché and shoot Hitler. He could take vaccines back in time and stop the Black Death before it started. The point is that with a time-machine the utilitarian greatest good for the greatest number includes all the many people of the past. Alice is no longer a consideration, only Bob's actions are.

I think perhaps the addition of time-travel detracts from your morality of stealing ideas.


All ethics have been developed in a world without time travel and all ethics devote themselves to a realisation of human happiness.

The utilitarian frameworks you specify all agree that ethics are the consequence of human rational thought, not divine rule. So result from an analysis of the consequences of behaviour in that world on human happiness.

As a consequence you could not develop an ethics which include time-travel without knowing the effect that time travel would have on the physical and sociological world, and the subsequent effects that these changes might have on the factors which result in human happiness.

As the possibility of time-travel would, without doubt, have a huge impact on both the physical world as we experience it and the sociological world we work with, to calculate an ethics based on it's existence in theory would be like calculating what the weather will be like next January the 18th based on knowing it rained today, there are simply too many unforeseeable consequences to even begin the task.

For some reason this does not prevent philosophers from engaging in such thought experiments ad nauseum (see teleportation paradox, Mary the colour blind scientist, the Chinese room). They all suffer from the same inherent problem, presuming that you could change only one thing about the world and that the rest of world and human intellect would remain largely the same.

Essentially, the direct answer to your question is that we could never possibly know in any useful sense what the ethical behaviour would be because in a world where time-travel exists so many other aspects of human behaviour will have also changed that deciding which behaviour would result in most human happiness by whatever metric you choose would be impossible.

  • all ethics devote themselves to a realisation of human happiness. seems kind of dubious considering the lengths you have to go to bring Kant's ethics under this description. Also, you don't need it for your answer since he's already specifying utilitarianism.
    – virmaior
    Jan 18, 2017 at 11:13
  • @Virmaior 1. I'd be interested to hear what objective Kant had other than human happiness, but that maybe outside the scope of comments. 2. More relevant here, the OP specified Utilitarianism and 'situational ethics' which attempts to define an 'intrinsic good', hence the necessity of the preamble.
    – user22791
    Jan 18, 2017 at 11:47
  • 1
    Er, plato.stanford.edu/entries/kant-moral , users.wfu.edu/hhardgra/kanteth.html both seem competent . I don't see the necessity of the inaccurate preamble. Even if we set aside Kant, it's questionable in applicability to lots of views (e.g. Stoic account of eudaimonia, Confucian account of *de, nearly all of Daoism's account of ethics, some species of divine command theory ... just to name a few).
    – virmaior
    Jan 18, 2017 at 13:34
  • @Virmaior From the first article you cite "Kant argued that this Highest Good for humanity is complete moral virtue together with complete happiness, the former being the condition of our deserving the latter.". Eudaimonia is often translated literally as happiness, the Stoic account is about what achieves it, not the aim itself. Divine command theory still posits heaven (a good place where you'll be happy) and hell (a bad place where you'll be sad). The point I'm making is not that all the ethical philosophies admit happiness is the objective, but that it is nonetheless.
    – user22791
    Jan 18, 2017 at 17:44
  • (1) Yes, Kant does say that, but if you'll note my sentence was seems kind of dubious considering the lengths you have to go to bring Kant's ethics under this description because this is a very minor claim in Kant's ethics and not the motivating consideration of ethics. (2) (1) Not all DCTs posit a heaven. (3) eudaimonia = happiness is probably a poor translation for the Stoic version where it's more closely aligned to ataraxia and has little to do with feelings (except insofar as the task is to learn to not respond with feeling).
    – virmaior
    Jan 19, 2017 at 1:16

There is no ethical problem whatsoever.

Physicists who study the theory of time-travel generally conclude that there are only two coherent ways it could work: (a) There is only a single internally-self-consistent timeline (the Nabokov Consistency Principle); or (b) Arrival of the time-traveller into the past creates a new branch on the timeline (the generalized Everett 'Many-Worlds' interpretation of QM).

There is no ethical problem in (a) because the time-traveller cannot do what he purports to set out to do: A single history cannot simultaneously recognize Alice as the inventor and recognize Bob as the inventor.

There is no ethical problem in (b) because (1) The version of Alice on the original timeline is entirely unaffected by the time-travel; and (2) The version of Alice on the alternate timeline has no more right to claim to be the inventor instead of Bob than she would if Bob had invented first through the natural course of events instead of through time-travel (how would she even know that her original was the inventor on the original timeline?).

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