(1) routine child vaccinations are effective. (2) if routine child vaccinations are effective then routine child vaccinations should be mandatory. -- with modus ponens from (1) (2) -- (3) routine child vaccinations should be mandatory.
routine child vaccinations are effective.
if routine child vaccinations are effective then routine child vaccinations should be mandatory.
routine child vaccinations should be mandatory? the vaccine provide inmunity to  the people  and prevents to contract the dissease.