Thursday, 4 November 2010

Fallacious arguments

In Sandec News No. 11 (published in August) there’s an article (pages 14−15) by Mbaye Mbéguéré, Pierre-Henri Dodane, Ousmane Sow and Doulaye Koné on “Financial Assessment of Dakar’s Sewer vs Faecal Sludge Management”. Here’s the intro. blurb:

In Senegal’s capital Dakar, with its approx. three million inhabitants, investment and O&M costs of the conventional, centralised sewer system are considerably higher than those of the on-site faecal sludge management (FSM) system. The income generated by user fees is insufficient to cover the expenses of the centralised sewer system, yet recovery of FSM charges appears easier.

The implication seems to be that, because FSM is cheaper than conventional sewerage, it’s a good thing to do. This is the “EcoSan fallacy” (see blog of 30 November 2008): if it (whatever "it" may be) is cheaper than conventional sewerage, then you should use it. The nonsense of this way of “thinking” is rapidly understood when you remember that everything’s cheaper than conventional sewerage, as John Kalbermatten found in the 1970s (see here) and as more recently determined in South Africa (here). What’s needed is a comparison between “it” (even “them”) and simplified sewerage.

All rather tiresome!