Here's David Chalmers addressing that claim:

the 2009 PhilPapers Survey surveyed around 1000 professional philosophers on answers to thirty important questions in philosophy, and typically found that answers to major questions were distributed something like 50-50 or 60-40 or 70-30, once agnostics and other intermediate options were removed. This suggests that at least where these questions are concerned, large collective convergence has not been achieved.

Now, you might say that these are the big questions of the moment and therefore are precisely those that are unanswered, so the result is no surprise. There is correspondingly little agreement on the current big questions of physics: the status of string theory, for example. To avoid this worry, it is important that the big questions be individuated not by current debate but by past importance.

To properly address this issue, we would need analogs of the PhilPapers survey in (for example) 1611, 1711, 1811, 1911, and 2011, asking members of the community of philosophers at each point first, what they take to be the big questions of philosophy, and second, what they take to be the answers to those questions (and also the answers to any big questions from past surveys). We would also need to have analogous longitudinal surveys in other fields: the MathPapers Survey, the PhysPapers survey, the ChemPapers Survey, the BioPapers Survey, and so on. And we would need a reasonable measure of convergence to agreement over time. I predict that if we had such surveys and measures, we would find much less convergence on answers to the big questions suggested by past surveys of philosophers than we would find for corresponding answers in other fields.