Daniel Dennett on The fine-tuning argument
Dennett argued that fine-tuning is an open scientific question, not evidence for design, and that the design inference is premature.
Dennett engaged the fine-tuning argument with the caution of a philosopher who respected science but mistrusted premature conclusions. He argued that the apparent fine-tuning of physical constants is genuinely interesting as a scientific observation, but that the inference to a designer is a leap — one that commits the same error as the biological design argument: it concludes 'therefore, God' when 'therefore, we don't yet understand' is more honest.
He was sympathetic to the multiverse hypothesis as a possible explanation, though he treated it as speculative rather than established. If a vast ensemble of universes with different constants exists, our observation of life-permitting constants is unsurprising — a straightforward application of anthropic reasoning. Whether the multiverse exists is an empirical question, and Dennett was content to wait for the physics to develop.
Dennett also pointed out the 'who designed the designer?' problem that Dawkins popularised. If the fine-tuning of constants requires explanation, then a being capable of setting those constants requires even more explanation. The design hypothesis does not terminate the explanatory regress — it deepens it.
“The argument from design has always been the most intuitively appealing argument for God — and the most vulnerable to scientific progress.”