Tim is not an economist, but he likes to play one on the internet
Anyway, he’s stated this more clearly than most economists I’ve known:
[Economics] assumes that that which is known is included into prices. What is unknown is what changes prices as it becomes known.
Intellectuals the world over like to complain about economics, but in that short quote there’s a testable implication that they all get off their asses and actually examine.
This is, since what we have available to us is by definition known (or at least not unknown), and what is unknown is not available to us at all, then you’ve found a problem with economics only if you can demonstrate that something was both known and not incorporated into prices.
I personally have examined that hundreds of times with actual data. I haven’t found any exceptions.† I know very few non-economists who have examined this even once. Yet, they continue to blither about how the behavior in markets that we observe just can’t be right.
† Well, actually, I did find a small one about twenty years ago. I found that gambling markets underestimated the ability of home teams in (American) football to win by less than a field goal. This discrepancy was not large or common enough for me to even justify putting my own money on the bets. In finance this is called an efficient market.