There's 100 or more planets in our solar system. The IAU's definition is unscientific garbage, voted on by only a handful of members when most of them were unavailable on purpose because a very small minority wanted to force Pluto into not being a planet anymore.
We can say definitively that the Earth is a planet. Earth is the paradigm example of what a planet is. All other planets must meet the same qualifications of the Earth to count as planets. This is true a priori.
This is one of two main ways we know the IAU decision to demote Pluto is invalid as science. First, the IAU made the decision based on a vote. Science isn't a democracy. You don't get to vote whether something is true or not. You have to test it and re-test it and other people have to test it. It doesn't matter if you have a "96% consensus" (actually something like 96% of abstracts that were looked at for the meta-analysis at the time mentioned anthropogenic global warming, they didn't endorse the idea, they just mentioned it), science isn't based on consensus. There was a consensus 500 years ago that the Sun orbited the Earth but that didn't make it true.
Fewer than 5% of IAU members actually voted on the decision anyway, so it's a crappy vote.
Second, the definition chosen for what qualifies as a planet is totally arbitrary and can be made to exclude the Earth. Planets must have "cleared the neighborhood around its orbit," which is a totally vapid and arbitrary criterion. The farther from a star a planet gets the more massive it needs to be to qualify as a planet because the amount of space it needs to "clear" becomes greater. By this definition if the Earth were placed in Pluto's orbit — 29-39 AU — then the Earth would not be considered a planet either because it wouldn't have enough mass to vacuum up the inner Kuiper Belt. But the Earth IS a planet where it is in space, meaning the third criterion doesn't signify anything intrinsic about the body itself. The definition of what is and is not a planet should not rest on some factor independent of the planet itself.
The third criterion for what qualifies a planet is not based on any intrinsic quality of the body itself but its relationship between it and its parent star. As such it is totally arbitrary and was designed (by admission) to disqualify Pluto and not based on sound scientific reasoning. The rule seemed carefully crafted so that “dwarf planets” like Pluto, Eres and Ceres (another body that was a planet for 50 years) didn’t make the cut.
The definition of "planet" also makes explicit reference to the Sun, so bodies orbiting other stars are by definition not planets, they're "exo-planets", which is more unscientific bullshit.
This isn’t exactly a rigorous scientific argument—so to give its decision the flavor of science, the IAU came up with a definition of “planet” so convoluted it seemed entirely arbitrary. To qualify as a planet, a body must orbit the Sun and be large enough to be at least roughly spherical—two rules that make sense. But it must also have gravitationally “cleared its neighborhood” of other bodies, meaning it has its orbital traffic lane all to itself, which Pluto doesn’t—at least during the most remote portion of its journey around the sun.