How do we justify getting excited about the prospect of spending billions on infrastructure improvements in the UK while thousands are dying before our eyes in Sudan for want of the most basic amenities?
With surprising ease, is the answer.
Projects like Crossrail are without doubt important for the UK economy and serve to drive the country forward.
But are they more important than providing clean water to the world's population?
As RedR founder and sustainability expert Peter Guthrie highlighted in his keynote presentation to the ICE presidential conference last week, costs and benefits can easily be measured. The tricky bit is judging the significance and relative value of different needs.
Yet it is these value judgements that lie at the heart of thinking about sustainability.
How important is it, for example, to cut carbon dioxide emissions or improve energy efficiency when people can fly to Spain and back for £60?
At the same conference, chairman of the ICE's presidential commission on sustainability Paul Jowett reassured delegates by predicting global warming would not be the downfall of the planet.
'Social breakdown will get us long before climate change, ' he said cheerily, pointing out the challenges presented by an increasingly urban world population.
To provide a clean water supply to the world's population, he explained, we would have to connect 275,000 people a day, every day for 12 years.
As a civil engineering challenge, it puts the construction of a few rail tunnels under London into context.
In this light, many may feel that projects like Crossrail are trivial or decadent. But the fact is that we are enthusiasts for modernising, updating and delivering better, more efficient solutions to problems.
Constructing big infrastructure projects is largely how we sell ourselves as (sustainable) civil engineers.
And to encourage the best and brightest into the profession we need to keep the message exciting.
The problem is keeping the right balance between presenting the truth about sustainability and scaring the living daylights out of people.
Yet civil engineers certainly have the skills to make a difference to people's lives in many ways and on many levels.
You do not have to look very far to realize that the UK - or the whole world for that matter - would be a much tougher place without the profession.
The work of pioneers like Bazalgette to improve living conditions and shape modern society did not stop. It just needs to be re-emphasised.
As Guthrie pointed out, 'sustainability requires the oxygen of activity around it'.
We cannot protect the planet and deliver better conditions for its inhabitants by sitting on our hands. But we do need to reassess the processes by which we make decisions on the value of infrastructure.
As a profession, we need to be thinking about the issues and expressing them as debate:
Jowett noted that change happens when people who don't usually speak, talk to people who do not usually listen.
We must therefore at least start to make ourselves heard.