Nothing quite extinguishes any mythology of accomplishment and pride in the achievements and sophistication of human civilisation than seeing an utterly isolated homeless person sleeping on a ramshackle mattress and amid their few ignominiously-bagged worldly belongings while early morning commuters rush to work around them. Of course, the visible (perhaps even ubiquitous, even in our affluent liberal democracies) existence of that poor soul who has fallen through such safety nets and community supports as still exist in the contemporary neoliberal maelstrom of fiendishly complicated economic participation and mutual obligations; that dishevelled and hungry individual (and there are so very many of them) is always a reminder that this, too, could quite easily be you.
This liminal existential awareness may be in part where that attempt to switch off to the relentlessly unfurling tragedy around us comes from – not just that when faced with so much transparent inequity and injustice it becomes a default-mode emotional state to feel that no one person can perhaps ever hope to significantly effect positive change in the face of such an efflorescence of misfortune. Other than that avoidance and deliberate ignorance of an entity or context as easily (or automatically) devolves into something of an oblivious state of ethical disregard, any repeated presentation of stimulus tends to have a diminishing effect on attention. It is a slow and yawning numbness and disregard for our fellow human being, a blindness to suffering and a resigned futility in the bare naked fact(s) of the failure of this collective human endeavour to protect, nourish and cultivate any human being who could (logically should) be the central variable, product and assertion of any sane equation of social or economic design and equitable systems-engineering.