For perhaps the same reason that polls show an uptick in support for gay marriage, a Pew Poll reveals majority support for making marijuana use legal.

I am hardly an expert but if you look at polls covering social issues over the past year, you will note that the winds are definitely blowing left - with the significant exception of abortion where pro-life forces have been able to hold their own and even increase support for life in some polls. If the change were based solely on demographics, the increase in support would be gradual - evolutionary instead of revolutionary.

But I wonder what these polls will look like six months or a year from now? Will the pendulum swing back?

For the first time in more than four decades of polling on the issue, a majority of Americans favor legalizing the use of marijuana. A national survey finds that 52% say that the use of marijuana should be made legal while 45% say it should not.

Support for legalizing marijuana has risen 11 points since 2010. The change is even more dramatic since the late 1960s. A 1969 Gallup survey found that just 12% favored legalizing marijuana use, while 84% were opposed.

he survey by the Pew Research Center, conducted March 13-17 among 1,501 adults, finds that young people are the most supportive of marijuana legalization. Fully 65% of Millennials -born since 1980 and now between 18 and 32 - favor legalizing the use of marijuana, up from just 36% in 2008. Yet there also has been a striking change in long-term attitudes among older generations, particularly Baby Boomers.

Half (50%) of Boomers now favor legalizing marijuana, among the highest percentages ever. In 1978, 47% of Boomers favored legalizing marijuana, but support plummeted during the 1980s, reaching a low of 17% in 1990. Since 1994, however, the percentage of Boomers favoring marijuana legalization has doubled, from 24% to 50%.

Generation X, born between 1965 and 1980, came of age in the 1990s when there was widespread opposition to legalizing marijuana. Support for marijuana legalization among Gen X also has risen dramatically - from just 28% in 1994 to 42% a decade later and 54% currently.

The Silent Generation continues to be less supportive of marijuana legalization than younger age cohorts. But the percentage of Silents who favor legalization has nearly doubled -from 17% to 32% - since 2002.

The deliterious effects of heavy marijuana usage are now well established in medical circles, although more casual usage appears less harmful according to many studies. Until the late 1990's, there had been little attention paid to marijuana in medical journals, largely because of studies done in the 1960's that showed the drug to be relatively harmless.

But more recent studies show heavy marijuana usage - 8 or more times a month - to have serious health consequences, including heavy users being more susceptible to depression, loss of short term memory, and damage to the lungs. There are also psychological effects including a loss of ambition and the possibility - still controversial - that marijuana is a "gateway drug" that makes one more likely to try more dangerous substances.

Do we really want to legalize a substance with these effects?