1.If capitalism causes poverty why can't welfare and social insurance fix that problem?
Because poverty is continually produced. At one point in the so called business cycle capitalist states can indeed afford themselves welfare and social benefits; but following this cycle, at another point (like the one we experience today) these will represent devastating costs for capital and will need to be scrapped. This also holds for parts of the workforce who become redundant, meaning that their labor is no longer useful for capital and so they become unemployed.
Consider also the fact that millions and millions of people around the world are simply redundant for the needs of capital without ever being integrated into global production (e.g. Africa and so on). Both what I wrote above and this is connected to the technological boosts in labor productivity. But then, the Western capitalist states and the banking sector can't simply afford to throw money at these people (if welfare and social benefits were to fix this problem) so the dreadful state remains.
2.Why is the profit motive ineffective for motivating workers and business owners.
Profit is a hell of an effective motive for business owners; it's the motive in fact.
But it has its own limits, and this limit is capital itself. In other words, when projected, expected profit rates are slim or even non-existent, investment won't occur.
From the standpoint of social reproduction, this is not only ineffective (if the criterion is welfare of all), but highly destructive in fact.
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“The possibility of securing for every member of society, by means of socialized production, an existence not only fully sufficient materially, and becoming day by day more full, but an existence guaranteeing to all the free development and exercise of their physical and mental faculties – this possibility is now for the first time here, but it is here.” Friedrich Engels
"The proletariat is its struggle; and its struggles have to this day not led it beyond class society, but deeper into it." Friends of the Classless Society
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