Baillie Gifford & Co. is the largest investor in Tesla Inc. after the electric car company’s maverick billionaire founder, Elon Musk. The Edinburgh-based fund manager owns about 7.7 percent of the company, a stake worth about $4.5 billion. You might think that such a committed investor would be 100 percent convinced Musk will confound critics of his automaking adventure. You’d be wrong: There is still a good possibility that Tesla will prove entirely and highly successful and the returns we make to that would outweigh the downside involved in all these complex tasks not working out. But I think one should always try to phrase things in terms of probabilities and payoffs rather than certainty.