Yes, quite obviously so, except perhaps to the most myopically anthropocentric. Why? Because it would be extremely presumptuous to think that in the entire universe the only planet capable of enabling the development of life is our own. The question asks, "could there be", not "is there", therefore the answer can only be yes.
Whether extraterrestrial life actually exists is a religious one at this point, at least until incontrovertible evidence demonstrates that it does, since the negative can not be proved until we have visited all parts of the Universe, quite a long time off I would imagine. Our religions tend to place Earth as central to the universe or to God's purpose now that most accept astronomy's revelations that the solar system isn't exactly significantly located.
If the Creator of the Universe wanted there to be life only on Earth, then that is the way it will be. But really, to go to all the trouble of creating something so immense, with billions of stars in this galaxy alone, and then put life on one planet only? How can any religion claiming that God is the Creator of all, the super fantastic being we should all worship, possibly think He or She could be so trivial, so small-minded, so unimaginative? Surely such a Creator would fill the universe with life, it can only be our desire to be supreme, our hubris, which could possibly allow us to think otherwise.
Those arguing against the possibility of extraterrestrial life ask, "If they exist, where are they?" This does not actually question the existence of extraterrestrial life, but the existence of INTELLIGENT extraterrestrial life. If there are other intelligences populating our galaxy, why have they not visited Earth in an indisputable manner? If Einsteinian space cannot be traversed at greater than the speed of light, should we not have at least detected communication signals from extraterrestrial civilizations in older parts of the galaxy, if they exist?
Unfortunately, all of our searching presumes that any other sapient species would wish to contact us. Or would at least not make any effort to hide their existence from us. Perhaps we should look at our history, examine how we have treated others of our own species based on the slightest of morphological differences and then consider again whether an intelligent extraterrestrial species would have the slightest desire to make our acquaintance.
Perhaps civilizations that have the technological capability to span stellar distances would have no problem excluding their past communications from entering the solar system. Perhaps we are legitimately excluded from the congress of sapient species. Perhaps the reason we only have unsubstantiated and unreliable reports of alien contacts are because the only aliens that are noticed visiting our planet are the equivalent of alien teenage joy riders and pranksters.