Reusable Cups: My Responsibility to Save the World.

My reusable mug

Do I, personally, have a responsibility to save the planet?

It seems a bold claim. After all, a simple recognition of the ability of human beings to alter the climate is not sufficient to create a responsibility to prevent anthropogenic climate change. This is because whilst the ends (saving the planet) might be worthwhile, the means (destroying every corporation? Murdering billions of people?) could be unreasonably burdensome.

I’ve previously argued (Juncture, 2019) that we definitely have some level of responsibility to respect the planet. But it’s not clear how far this extends.Here, I will briefly look at how we conceptualise looking after the planet, understanding our burdens and how these notions are reflected through a simple reusable cup.

First, a question: If my intention is good, is the act good?

If I intend to help an old lady cross a road, but inadvertently trip her, leading to her breaking an arm, am I a good person? Am I a good person if I break into a house, intending to steal a laptop, but see the occupant having a heart attack and phone an ambulance before fleeing?

Answering ‘yes, that makes you a good person’, to either of these questions seems intuitively wrong, despite the fact that the intention in each is more clearly right or wrong. The notion of separating one’s intention from the outcome in order to evaluate its goodness seems unreflective of our moral reality. Only if our intention and outcome are good we would generally say that a given behaviour is good. So what does that mean for reusable/disposable cups?

Well, for many of us, our intention with the purchasing of a mug is surely good. We accept the notion, presented to us in the media and by our peers, that to use a reusable mug represents an inherently good thing to do. In doing so, we are not considering the benefits to ourselves (through double-stamps at Caffe Nero, or 25p off at Starbucks), but rather the inherently good nature of the act. This is a kind of good that is necessarily difficult to define, and that has flummoxed philosophers and the general population alike. But we can conceive of it as simply as: it is good to own a reusable mug because it demonstrates a concern for the planet and an awareness of the harm that single-use cups have on the environment. (This is an wonderful oversimplification, but those interested should read the Stanford Encyclopedia links at the bottom of this piece.)

So what then of the outcome. As stated, for an act to generally be conceived to have been good or worthwhile, the intention and action need to both be seen to be good.

With reusable cups, it is generally thought that the outcome is good. And depending on how we choose to look at it, that holds true. For example, research suggests that for some mugs as little as 20 uses means that they have a smaller carbon footprint than the equivalent number of disposable cups. Generally, anytime one uses their reusable mug in excess of 100 times, they are in the clear. (Pierre-Olivier Roy, 2017)

However, this is complicated by the notion that owning a reusable cup might encourage the consumer to purchase a greater number of hot drinks, an act which obviously has a detrimental environmental effect. Indeed, the market for eco-conscious, reusable goods such as straws has exploded in the last decade. Thus although behavioural modification is nearly impossible to evaluate and measure, it is nevertheless a consideration.

We might argue that the question of outcome being so difficult to ascertain results in a table that looks more like this:

This seems to more accurately reflect our moral reality. We cannot always know what the outcomes of our actions will be with any significant degree of certainty. Nor can we always ascertain what others intentions are with their actions. What we can do, however, is consider the intentions behind our behaviour, and the outcomes we hope and expect to achieve and judge for ourselves whether we are doing the right thing. Naturally, a lot rests on what we mean by the word ‘unclear’ in this situation, but the principle holds: if we have good intention, but lack certainty as to the outcome, we can generally conceive of having done a good thing.

So in answer to the original question posed, do I have a responsibility to save the planet? Whilst we could delineate between moral duties and moral responsibilities, that discussion is unnecessary for making a determination about what obligations there are upon me. If we conclude that I am responsible for saving the planet, that would leave no room for personal agency, decision-making or the pursuit of a worthwhile life. Any recognisable duty requires reasonable burdens.

A better way of framing the discussion, then, is to ask, do we have good reasons to use reusable cups to help save the planet? This, I think, is more readily answerable. Indeed, the very practice of asking such a question has important implications for how we consider the environment and our impact upon it. Yes, we have good reasons for using a reusable mug. Namely, it is likely, over a long lifetime, to reduce our consumption of single-use items and reduce our carbon footprint. Additionally, it is a good thing to do to show respect to the planet in ways that are not so overly demanding as to be objectionable (Darwall, 1977). In other words, when an act is so insignificant to the actor as buying a mug that they can wash and reuse, but the potential gains are so significant for the planet as a whole, we have reasons to act that way.

There is no doubt that many acts and actors purport to respect the planet whilst failing too. The virtue-signalling nature of some actors is plain to see (Boris Johnson gets a disposable mug snatched away from him on the Campaign trail) and there are obvious selfish benefits to owning a mug (50p off at Pret). However, we ought to trust people to be sufficiently mindful, considerate and well-intentioned so as to be purchasing mugs in the hope and expectation of lessening their impact on the planet, nature and our environment.

For what it’s worth (apparently, £20 or so), the mug itself is lovely. Glass means that it is easy to clean and doesn’t impart taste on the coffee. The cork band, which could maybe be slightly larger to accommodate all my fingers, is a clever, tasteful and elegant sleeve. The lid whilst not water-tight, is sufficient to keep the contents warm and function as a reliable spout as well as being easy to disassemble for washing. It makes a contrived claim to being a ‘barista standard cup’ which to me, as a part-time barista, is something I can’t help but laugh at.

I purchased my reusable mug in September and have used it maybe one hundred times. Providing I don’t drop it, I can certainly see it lasting me for several hundred more coffees. So, if you are looking for a reusable mug, this one might be for you...

To conclude, is assessing our responsibility to save the planet, we should consider two things. Firstly, what can we be responsible for? I have argued that we can only be responsible for things that have burdens that are comparable to their ends. That is, only if something is really good, can we argue that it is necessary for us to do. The second consideration, however, is about how we ascertain what a good thing is. I have argued it is composed of our intention and outcome. Naturally, however, the outcome is not always clear, or might be the total opposite of our intention. As such, we should do acts that are (i) well-intentioned and (ii) produce measurably good outcomes. Indeed, such acts, can, depending on the extent of those outcomes and the demanding nature of the act itself, be obligatory. One such example is getting yourself a reusable cup.

In an interesting development, some cafes are now denying people the opportunity to use their reusable mugs in the wake of the COVID-19 outbreak. This adds a further philosophical question regarding whether the detriment to public health is sufficient to justify the imposition of a ban on reusable mugs designed to minimise our environmental impact. This is, however, a question for another day...



Darwall, S. (1977). “Two Kinds of Respect.” Ethics, 88(1), 36-49.

Rogers, J. (2019). “Is There A Cogent Solution to the Problem of Inconsequentialism?” Juncture, 2(2), 38-44.

Roy, P. (2017) “Reusable or Disposable: Which coffee cup has a smaller footprint?” Anthropocene Magazine. (accessed March 22, 2020).

Further Reading:

Talbert, M. “Moral Responsibility.” The Stanford Encyclopedia of Philosophy (Winter 2019 Edition), (accessed March 22, 2020).

Zimmerman, M. and Bradley, B. "Intrinsic vs. Extrinsic Value", The Stanford Encyclopedia of Philosophy (Spring 2019 Edition), (accessed March 22, 2020).