...partly out of courtesy and partly because I've had enough of moronics for now...
...he asked "Doesn't anyone remember what happened in the past? If we don't learn from our mistakes, we will be doomed to repeat them again and again."
It seems to me, as I said in another thread, there are some people who can learn from other's mistakes, some who learn from their own mistakes and some who can't learn at all. Most people are a mixture of these.
Learning from history is a specialised form of learning from the mistakes of others. And quite often this is collective learning rather than just individual learning. It's much harder than any of the other forms of learning for several reasons.
Firstly, there has to be the will to begin to learn. This is hard enough in the case of an individual. In the case of groups where mass opinion may be manipulated by contrary parties and where stimulating information may be removed all together, it can seen nigh on impossible at times.
And then there has to be focus. Learning from history normally means some kind of comparison with current affairs, and unless the affairs are so dominant (as they have been of late) that they exclude nearly everything else, they are often drowned out or considerably lessened in impact by the rest of what's going on. Again it takes will to keep focus, and quite frankly this is more than the average citizen will find time for.
Which is where special interests groups come in, keeping their particular flames alive. Yet even they don't continue for centuries. The likes of Amnesty International, this year celebrating its 40th anniversary, are rare enough.
The answer to H Tower's question perhaps lies in an assumption implicit in the question itself. Who is the "we" that is supposed to learn? Should - or even can - humanity in general, or a society in particular necessarily be progressing in a direction? Does that really make sense? Perhaps in some cases it does - I doubt if we are about to lose Women's Suffrage for example - but in others I really don't think that notion of progress (and therefore group learning for ever) applies.
A society might be seen to be made out of individuals, and perhaps there are some lessons which really do have to be learnt time and time again. Because they apply to groups, and while individuals may persist and learn their individual lessons, groups are never the same from decade to decade and can never retain what has been learnt for certain.