The only thing Bogle talks more passionately about is speculation. He decries ETFs for allowing broad speculation to distort market values. He supports long term investing, despite market volatility, saying "Don't worry, because corporate America is going to be there at the end of our lifetime."
Bogle prefers mutual funds as holders tend to be more long term investors than ETFs. He points to 10,000% turnover in SPY as how speculative an instrument ETFs have become. What matters here is the investors behavior. ETFs do offer more transparency and flexibility to investors than mutual funds. Short term trading and speculation are the bad behavior, a long term investor should be a priori neutral to the vehicle. Once an investor has determined the asset classes they would like to invest in, the most appropriate vehicle can be selected - be it an ETF or a mutual fund.
